Class 10 Magnetic Effects of Electric Current MCQ

Class 10 Magnetic Effects of Electric Current MCQ

Class 10 Science Magnetic Effects of Electric Current Question Bank

A. Multiple Choice Questions (MCQs)

1. A current-carrying conductor produces:

A. Only heat
B. Only light
C. A magnetic field
D. Sound waves

Answer: C

2. The instrument commonly used to detect the direction of a magnetic field is:

A. Ammeter
B. Compass
C. Voltmeter
D. Rheostat

Answer: B

3. Outside a bar magnet, magnetic field lines are conventionally directed:

A. South to North
B. North to South
C. East to West
D. West to East

Answer: B

4. Inside a bar magnet, magnetic field lines run from:

A. North to South
B. South to North
C. East to West
D. Centre to poles

Answer: B

5. A region where the magnetic influence of a magnet can be detected is called:

A. Electric field
B. Magnetic field
C. Electric circuit
D. Potential field

Answer: B

6. Magnetic field lines are closer together in regions where the field is:

A. Weaker
B. Zero
C. Stronger
D. Changing direction

Answer: C

7. Two magnetic field lines cannot intersect because:

A. They are imaginary
B. Magnetic fields cannot exist in space
C. A compass needle cannot point in two directions simultaneously
D. Magnets repel all field lines

Answer: C

8. Around a straight current-carrying wire, magnetic field lines are:

A. Straight and parallel
B. Radial
C. Concentric circles
D. Elliptical

Answer: C

9. If the current through a straight conductor is increased, its magnetic field:

A. Decreases
B. Increases
C. Remains unchanged
D. Becomes zero

Answer: B

10. If the compass is moved farther from a current-carrying straight wire, the magnetic field detected by it:

A. Increases
B. Decreases
C. Remains constant
D. Reverses automatically

Answer: B

11. Reversing the direction of current in a conductor:

A. Has no effect on the magnetic field
B. Reverses the magnetic field direction
C. Removes the magnetic field
D. Doubles the magnetic field

Answer: B

12. The direction of magnetic field around a straight current-carrying conductor can be found using:

A. Fleming’s left-hand rule
B. Right-hand thumb rule
C. Ohm’s law
D. Joule’s law

Answer: B

13. According to the right-hand thumb rule, the thumb represents:

A. Magnetic field
B. Force
C. Current
D. Resistance

Answer: C

14. According to the right-hand thumb rule, curled fingers indicate:

A. Current
B. Magnetic field direction
C. Force
D. Voltage

Answer: B

15. When a straight conductor is bent into a circular loop, the magnetic effects of different sections at the centre:

A. Cancel completely
B. Act in the same direction
C. Become zero
D. Become random

Answer: B

16. A coil with more circular turns generally produces:

A. A weaker magnetic field
B. A stronger magnetic field
C. No magnetic field
D. Only an electric field

Answer: B

17. A solenoid is:

A. A single straight wire
B. A coil of many closely wound circular turns
C. A permanent magnet only
D. A battery

Answer: B

18. The magnetic field of a current-carrying solenoid resembles that of:

A. A charged sphere
B. A bar magnet
C. A resistor
D. A compass only

Answer: B

19. The magnetic field inside a long solenoid is approximately:

A. Random
B. Zero
C. Uniform
D. Circular only

Answer: C

20. A solenoid can be used to make an electromagnet by placing inside it:

A. Plastic
B. Glass
C. Soft iron
D. Rubber

Answer: C

21. A current-carrying conductor placed in a magnetic field experiences:

A. A force
B. Only heat
C. No effect
D. Only light

Answer: A

22. The direction of force on a current-carrying conductor depends on:

A. Current only
B. Magnetic field only
C. Both current and magnetic field directions
D. Resistance only

Answer: C

23. The force on a current-carrying conductor is greatest when the current and magnetic field are:

A. Parallel
B. Perpendicular
C. In the same direction
D. Opposite but parallel

Answer: B

24. Fleming’s left-hand rule gives the direction of:

A. Magnetic field around a wire
B. Force on a current-carrying conductor
C. Resistance
D. Potential difference

Answer: B

25. In Fleming’s left-hand rule, the thumb indicates:

A. Current
B. Magnetic field
C. Force or motion
D. Resistance

Answer: C

26. In Fleming’s left-hand rule, the forefinger represents:

A. Current
B. Magnetic field
C. Force
D. Voltage

Answer: B

27. In Fleming’s left-hand rule, the middle finger represents:

A. Current
B. Magnetic field
C. Force
D. Resistance

Answer: A

28. Which device is associated with the magnetic effect of current?

A. Electric motor
B. Glass rod
C. Thermometer
D. Measuring cylinder

Answer: A

29. Domestic appliances are generally connected:

A. In series
B. In parallel
C. In a single loop only
D. Without switches

Answer: B

30. Parallel connection of domestic appliances allows them to:

A. Always operate together
B. Receive equal potential difference and operate independently
C. Receive zero voltage
D. Have no separate switches

Answer: B

31. The earth wire is primarily used as:

A. A source of electricity
B. A safety path for leakage current
C. A heating element
D. A magnetic field detector

Answer: B

32. A fuse protects a circuit mainly from:

A. Low temperature
B. Excessive current
C. Low resistance only
D. Magnetic poles

Answer: B

33. When excessive current causes a fuse wire to melt, the circuit:

A. Becomes stronger
B. Remains unchanged
C. Breaks
D. Produces more current

Answer: C

34. A short circuit can cause:

A. A sharp increase in current
B. A sharp decrease in current
C. No current
D. Constant low current

Answer: A

35. Connecting too many appliances to one socket may cause:

A. Overloading
B. Magnetisation
C. Cooling
D. Reduced voltage to zero

Answer: A

36. MRI is an application of magnetism in:

A. Agriculture
B. Medicine
C. Transport
D. Communication only

Answer: B

B. Fill in the Blanks

  1. A current-carrying wire produces a __________ field.
    Answer: magnetic
  2. A compass needle behaves like a small __________.
    Answer: magnet
  3. The region around a magnet where its magnetic influence can be detected is called the __________ field.
    Answer: magnetic
  4. Outside a bar magnet, field lines emerge from the __________ pole.
    Answer: north
  5. Outside a bar magnet, field lines enter the __________ pole.
    Answer: south
  6. Magnetic field lines form __________ curves.
    Answer: closed
  7. Closer magnetic field lines indicate a __________ magnetic field.
    Answer: stronger
  8. Field lines around a straight current-carrying conductor are __________ circles.
    Answer: concentric
  9. Increasing current through a conductor increases the strength of its __________ field.
    Answer: magnetic
  10. The magnetic field becomes weaker as the distance from the conductor __________.
    Answer: increases
  11. The __________ thumb rule gives the direction of magnetic field around a straight current-carrying wire.

Answer: right-hand

  1. In the right-hand thumb rule, the thumb points in the direction of __________.

Answer: current

  1. A coil containing many closely wound turns is called a __________.

Answer: solenoid

  1. A current-carrying solenoid behaves similarly to a __________ magnet.

Answer: bar

  1. The magnetic field inside a long solenoid is approximately __________.

Answer: uniform

  1. An electromagnet can be made using a solenoid and a __________ iron core.

Answer: soft

  1. A current-carrying conductor placed in a magnetic field experiences a __________.

Answer: force

  1. The force on a conductor is maximum when current and magnetic field are at __________ angles.

Answer: right

  1. __________ left-hand rule determines the direction of force on a current-carrying conductor.

Answer: Fleming’s

  1. In Fleming’s left-hand rule, the thumb indicates the direction of __________.

Answer: force/motion

  1. Domestic appliances are connected in __________.

Answer: parallel

  1. The __________ wire is an important safety connection in domestic circuits.

Answer: earth

  1. A fuse protects a circuit against excessively high __________.

Answer: current

  1. Direct contact between live and neutral wires may cause a __________ circuit.

Answer: short

  1. Excessive current may cause a fuse wire to __________.

Answer: melt

  1. Too many appliances connected to one socket can cause __________.

Answer: overloading

  1. Magnetic effects have an important application in medicine called __________.

Answer: MRI

C. True or False

  1. A current-carrying conductor produces a magnetic field.
    True
  2. Magnetic field lines around a straight current-carrying wire are radial.
    False
  3. Increasing current strengthens the magnetic field around a conductor.
    True
  4. Magnetic field becomes weaker as distance from the current-carrying wire increases.
    True
  5. Reversing current reverses the magnetic field direction.
    True
  6. Magnetic field lines can intersect one another.
    False
  7. Field lines are more crowded where the magnetic field is stronger.
    True
  8. A solenoid has a magnetic field similar to that of a bar magnet.
    True
  9. The field inside a long solenoid is approximately uniform.
    True
  10. An electromagnet can be produced using a current-carrying solenoid.
    True
  11. A current-carrying conductor never experiences force in a magnetic field.
    False
  12. The force on the conductor is greatest when current and magnetic field are perpendicular.
    True
  13. Fleming’s left-hand rule determines the direction of magnetic force.
    True
  14. The right-hand thumb rule determines the direction of force on a conductor.
    False
  15. Household appliances are connected in parallel.
    True
  16. An earth wire is used as a safety measure.
    True
  17. A fuse increases the current during a short circuit.
    False
  18. A fuse melts when excessive current produces sufficient heating.
    True
  19. Connecting too many appliances to one socket may result in overloading.
    True
  20. MRI is an application of magnetism in medicine.
    True

D. Match the Following

Column AColumn B
1. Compassa. Safety device
2. Right-hand thumb ruleb. Detects magnetic direction
3. Solenoidc. Direction of magnetic field around current
4. Fleming’s left-hand ruled. Coil of many turns
5. Fusee. Direction of force
6. Earth wiref. Safety against leakage
7. MRIg. Medical application
8. Electromagneth. Magnet produced using current

Answers:
1-b, 2-c, 3-d, 4-e, 5-a, 6-f, 7-g, 8-h

E. Very Short Answer Questions

1. What is a magnetic field?

Answer: The region around a magnet where its magnetic influence can be detected.

2. What does a compass detect?

Answer: It helps indicate the direction of a magnetic field.

3. What happens to a compass near a current-carrying wire?

Answer: Its needle gets deflected.

4. What shape do magnetic field lines around a straight current-carrying wire have?

Answer: Concentric circles.

5. What happens to magnetic field strength when current increases?

Answer: It increases.

6. What happens to magnetic field strength as distance from a straight conductor increases?

Answer: It decreases.

7. Name the rule used to determine the magnetic field direction around a straight conductor.

Answer: Right-hand thumb rule.

8. What is a solenoid?

Answer: A coil of many closely wound circular turns of insulated wire arranged in a cylindrical form.

9. What does a current-carrying solenoid resemble?

Answer: A bar magnet.

10. What is an electromagnet?

Answer: A magnet produced by magnetising a suitable magnetic material using the field of a current-carrying coil.

11. What happens when a current-carrying conductor is placed in a magnetic field?

Answer: It experiences a force.

12. When is this force maximum?

Answer: When the conductor/current direction is perpendicular to the magnetic field.

13. Name the rule used to find the direction of force on a current-carrying conductor.

Answer: Fleming’s left-hand rule.

14. How are domestic appliances connected?

Answer: In parallel.

15. What is the purpose of an earth wire?

Answer: It provides a safe low-resistance path for leakage current.

16. What is a fuse?

Answer: A safety device that breaks the circuit when excessive current flows.

17. What is short circuiting?

Answer: A condition in which a fault creates a very low-resistance path and causes a sharp rise in current.

18. Name one medical application of magnetism.

Answer: MRI.

F. Short Answer Questions

1. Why does a compass needle deflect near a current-carrying wire?

Answer: Current flowing through the wire produces a magnetic field. This field interacts with the magnetic compass needle and causes it to deflect.

2. Why are magnetic field lines useful?

Answer: They provide a visual representation of a magnetic field. Their direction indicates the field direction, while their spacing gives an idea of field strength.

3. Why do magnetic field lines not intersect?

Answer: At any point, a magnetic field has only one definite direction. If two field lines intersected, a compass placed there would have to point in two directions simultaneously.

4. What happens when the current through a straight conductor is reversed?

Answer: The direction of its magnetic field is also reversed.

5. How can the magnetic field of a circular coil be increased?

Answer: Increasing the number of turns strengthens the magnetic field because the magnetic effects of the individual turns add together.

6. Why does a solenoid resemble a bar magnet?

Answer: The magnetic field pattern around a current-carrying solenoid has two ends behaving like north and south poles, giving it a field pattern similar to a bar magnet.

7. Why is the magnetic field inside a long solenoid considered uniform?

Answer: Its field lines inside are approximately parallel and similarly spaced, indicating nearly the same field strength and direction throughout the region.

8. What factors determine the direction of force on a current-carrying conductor?

Answer: The direction of current and the direction of the magnetic field determine the force direction.

9. What happens to the force if the direction of current is reversed?

Answer: The direction of the force is reversed.

10. What happens if the magnetic field direction is reversed?

Answer: The direction of force on the conductor is reversed.

11. Why are household appliances connected in parallel?

Answer: Parallel connection allows appliances to receive the same potential difference and operate independently.

12. Why is earthing important for metallic appliances?

Answer: If current leaks onto the metallic body, the earth wire provides a low-resistance path to the ground and reduces the risk of severe electric shock.

13. How does a fuse protect an electrical circuit?

Answer: Excessive current heats the fuse wire. When the heating is sufficient, the fuse melts and breaks the circuit, stopping the excessive current.

14. Give two causes of overloading.

Answer: Connecting too many appliances to one socket and an abnormal increase in supply voltage.

G. Give Reasons

1. A compass needle deflects near a current-carrying conductor.

Reason: Electric current produces a magnetic field around the conductor.

2. Magnetic field lines are crowded near the poles of a bar magnet.

Reason: Crowded field lines represent a stronger magnetic field.

3. The magnetic field direction changes when current direction is reversed.

Reason: The magnetic field direction depends on the direction of current.

4. A coil with more turns produces a stronger magnetic field.

Reason: The magnetic effects produced by individual turns add together.

5. A current-carrying conductor moves when placed in a magnetic field.

Reason: The magnetic field exerts a force on the current-carrying conductor.

6. Domestic appliances are connected in parallel.

Reason: Parallel connection provides the same potential difference across appliances and allows independent operation.

7. A fuse is used in domestic circuits.

Reason: It breaks the circuit when excessive current causes the fuse element to melt.

8. Metallic appliances are connected to an earth wire.

Reason: Earthing provides a safe low-resistance path for leakage current.

H. Assertion–Reason Questions

Choose:

A. Both A and R are true, and R correctly explains A.
B. Both A and R are true, but R does not correctly explain A.
C. A is true, but R is false.
D. A is false, but R is true.

1.

Assertion: A current-carrying wire produces a magnetic field.
Reason: A compass needle can deflect when placed near the wire.

Answer: A

2.

Assertion: Magnetic field lines do not intersect.
Reason: A compass needle cannot point in two different directions at the same point.

Answer: A

3.

Assertion: The magnetic field around a straight conductor weakens with distance.
Reason: The magnetic field is stronger near the conductor.

Answer: B

4.

Assertion: Increasing current increases the magnetic field around a conductor.
Reason: Magnetic field strength at a given point depends on current.

Answer: A

5.

Assertion: A current-carrying solenoid can behave like a bar magnet.
Reason: Its magnetic field pattern has two opposite ends corresponding to magnetic poles.

Answer: A

6.

Assertion: A current-carrying conductor can experience force in a magnetic field.
Reason: Magnetic fields can exert force on current-carrying conductors.

Answer: A

7.

Assertion: The force on a conductor is greatest when current and magnetic field are perpendicular.
Reason: Experiments show maximum displacement in this orientation.

Answer: A

8.

Assertion: Household appliances are connected in parallel.
Reason: Appliances can then operate independently.

Answer: A

9.

Assertion: A fuse protects circuits from excessive current.
Reason: The fuse can melt and interrupt the circuit when excessive current flows.

Answer: A

10.

Assertion: Connecting too many appliances to one socket may cause overloading.
Reason: Excessive connected load can result in excessive current.

Answer: A

I. Conceptual / Application-Based Questions

1. A student increases the current through a straight wire. What happens to the compass deflection nearby?

Answer: The deflection increases because the magnetic field becomes stronger.

2. A compass is moved farther from a current-carrying wire. Predict the change in deflection.

Answer: The deflection decreases because the magnetic field becomes weaker with distance.

3. A student reverses the battery connections in a circuit containing a straight wire. What happens to the magnetic field?

Answer: Its direction reverses because the current direction has reversed.

4. Two coils have the same current, but one has more turns. Which produces the stronger magnetic field?

Answer: The coil with more turns.

5. A soft iron piece is inserted into a current-carrying solenoid. What is produced?

Answer: An electromagnet is formed.

6. A conductor is placed in a magnetic field, but current is not flowing through it. Will the magnetic force described in this chapter act due to the current-carrying effect?

Answer: No. The force discussed here requires a current-carrying conductor.

7. A conductor experiences force in a magnetic field. The current direction is reversed while the field remains unchanged. What happens?

Answer: The force reverses direction.

8. The magnetic field direction is reversed while the current remains unchanged. What happens to the force?

Answer: The force reverses direction.

9. Why is a separate switch provided for household appliances?

Answer: Parallel connection allows each appliance to be switched independently.

10. What danger may result from a damaged insulation that connects live and neutral wires?

Answer: It can produce a short circuit and cause a sharp increase in current.

J. Case-Based Questions

Case Study 1 — Straight Conductor

A student places a compass near a straight copper wire. When current is passed through the wire, the compass needle deflects. The student then increases the current and observes a larger deflection. Finally, the compass is moved farther away.

Questions

1. Why does the compass deflect?
Answer: The current produces a magnetic field around the wire.

2. What happens to the magnetic field when current increases?
Answer: It becomes stronger.

3. What happens when the compass is moved farther away?
Answer: The magnetic field becomes weaker and the deflection decreases.

4. What is the shape of the field lines around the wire?
Answer: Concentric circles.

Case Study 2 — Solenoid

A coil consists of many closely wound turns of insulated wire. When current passes through it, its magnetic field resembles that of a bar magnet. A soft iron piece is placed inside the coil.

Questions

1. What is the coil called?
Answer: A solenoid.

2. What does its magnetic field resemble?
Answer: The magnetic field of a bar magnet.

3. What happens when soft iron is placed inside it?
Answer: It becomes magnetised and an electromagnet is formed.

4. What is the nature of the magnetic field inside a long solenoid?
Answer: Approximately uniform.

Case Study 3 — Force in a Magnetic Field

A current-carrying rod is placed between the poles of a strong magnet. The rod moves. When the current direction is reversed, its movement reverses as well.

Questions

1. Why does the rod move?
Answer: It experiences a magnetic force.

2. What determines the direction of the force?
Answer: The directions of current and magnetic field.

3. What happens when current is reversed?
Answer: The force direction reverses.

4. Which rule determines the force direction?
Answer: Fleming’s left-hand rule.

Case Study 4 — Domestic Circuit

A family connects several appliances to a household circuit. Each appliance has an independent switch. The circuit also contains an earth connection and a fuse.

Questions

1. How are the appliances connected?
Answer: In parallel.

2. Why can each appliance be operated independently?
Answer: Parallel connection gives each appliance its own branch and switch.

3. What is the purpose of the earth wire?
Answer: It provides a safe path for leakage current.

4. What is the purpose of the fuse?
Answer: It protects the circuit against excessive current.

5. What happens to the fuse when excessive current flows?
Answer: It heats up and melts, breaking the circuit.

K. Diagram-Based Questions

1. Draw the magnetic field lines around a bar magnet.

Expected features:

  • Lines emerge from North outside the magnet.
  • Lines enter South outside the magnet.
  • Lines return through the magnet from South to North.
  • Lines form closed curves.
  • Lines are denser near the poles.

2. Draw the field pattern around a straight current-carrying conductor.

Expected feature:
Concentric circles centred on the conductor.

3. Draw the magnetic field pattern of a current-carrying solenoid.

Expected features:

  • Pattern resembles a bar magnet.
  • One end behaves as North.
  • Other end behaves as South.
  • Field inside is approximately uniform.

4. Draw three mutually perpendicular directions for Fleming’s left-hand rule.

Label:

  • Forefinger → Magnetic field
  • Middle finger → Current
  • Thumb → Force/motion

5. Draw a simple domestic circuit showing:

  • Live wire
  • Neutral wire
  • Earth wire
  • Fuse
  • Switch
  • Appliances connected in parallel

L. Rule-Based Questions

1. State the right-hand thumb rule.

Answer: Hold a current-carrying straight conductor in the right hand with the thumb pointing along the current. The curled fingers indicate the direction of the magnetic field.

2. State Fleming’s left-hand rule.

Answer: Stretch the thumb, forefinger and middle finger of the left hand mutually perpendicular. If the forefinger points along the magnetic field and the middle finger along the current, the thumb gives the direction of force or motion.

3. Which rule determines the field around a straight current-carrying conductor?

Answer: Right-hand thumb rule.

4. Which rule determines force direction on a current-carrying conductor in a magnetic field?

Answer: Fleming’s left-hand rule.

5. What rule is also associated with the corkscrew analogy?

Answer: The right-hand thumb rule / Maxwell’s corkscrew rule.

M. Higher-Order Thinking Questions

1. Why does increasing the number of turns in a coil increase its magnetic field?

Answer: Each turn produces a magnetic field in the same overall direction, so their effects combine and strengthen the resulting field.

2. Why does reversing current reverse the magnetic effect?

Answer: The direction of the magnetic field produced by a conductor depends on the direction of current. Reversing current therefore reverses the field.

3. Why can a solenoid be used as an electromagnet?

Answer: Current through the solenoid creates a strong magnetic field, which can magnetise a suitable soft iron core placed inside it.

4. Why does a current-carrying conductor experience force in a magnetic field?

Answer: The magnetic field interacts with the magnetic effect associated with the current, producing a force on the conductor.

5. Why does the direction of force change when either current or magnetic field is reversed?

Answer: The force direction depends on both current direction and magnetic field direction.

6. Why are field lines useful even though they are imaginary?

Answer: They provide a convenient way to represent both the direction and relative strength of a magnetic field.

7. Why is a fuse placed in an electrical circuit?

Answer: It provides protection by breaking the circuit when excessive current causes the fuse element to melt.

8. Why can overloading be dangerous?

Answer: Excessive current can cause excessive heating and may damage the circuit or appliances.

N. Long Answer Questions

1. Explain the magnetic field produced by a straight current-carrying conductor.

Answer points:

  • Current through a conductor produces a magnetic field.
  • The field lines form concentric circles around the conductor.
  • Increasing current increases field strength.
  • Increasing distance decreases field strength.
  • Reversing current reverses the magnetic field direction.
  • The right-hand thumb rule determines its direction.

2. Explain the magnetic field of a current-carrying solenoid.

Answer points:

  • A solenoid consists of many closely wound turns.
  • Current through it creates a magnetic field.
  • Its field pattern resembles a bar magnet.
  • One end behaves as North and the other as South.
  • Field lines inside a long solenoid are nearly parallel.
  • Therefore, the field inside is approximately uniform.
  • A soft iron core can be magnetised to produce an electromagnet.

3. Explain the force on a current-carrying conductor in a magnetic field.

Answer points:

  • A current-carrying conductor placed in a magnetic field experiences force.
  • Force direction depends on current direction and magnetic field direction.
  • Reversing current reverses force direction.
  • Reversing the magnetic field also reverses force direction.
  • Maximum force occurs when current and field are perpendicular.
  • Fleming’s left-hand rule determines the direction of force.

4. Explain the important features of a domestic electric circuit.

Answer points:

  • Electrical supply enters the house through the mains.
  • Live and neutral wires form the supply circuit.
  • Appliances are connected in parallel.
  • Separate switches allow independent operation.
  • The earth wire provides protection against leakage current.
  • A fuse protects the circuit from excessive current.
  • Short circuits and overloading can cause dangerous increases in current.

O. Compare / Differentiate

1. Right-Hand Thumb Rule vs Fleming’s Left-Hand Rule

Right-Hand Thumb RuleFleming’s Left-Hand Rule
Finds magnetic field directionFinds force direction
Used around current-carrying conductorUsed for a conductor in a magnetic field
Thumb represents currentMiddle finger represents current
Fingers represent magnetic fieldForefinger represents magnetic field
—Thumb represents force/motion

2. Short Circuit vs Overloading

Short CircuitOverloading
May occur due to direct contact between live and neutral wiresMay occur when too many appliances are connected
Current rises sharplyExcessive current flows through the circuit
Can damage circuit/appliancesCan cause excessive heating and damage
Fuse can protect against the resulting excessive currentFuse can protect against excessive current

3. Magnetic Field vs Magnetic Field Lines

Magnetic FieldMagnetic Field Lines
Region of magnetic influenceImaginary representation of the field
Exists around a magnet/current-carrying conductorUsed to show direction and relative strength
Has direction and magnitudeDirection is represented by the line orientation

P. One-Word / One-Term Questions

  1. Scientist associated with the discovery linking current and magnetism?
    Oersted
  2. Instrument containing a small magnet used to indicate magnetic direction?
    Compass
  3. Region around a magnet where magnetic influence acts?
    Magnetic field
  4. Imaginary lines used to represent a magnetic field?
    Magnetic field lines
  5. Rule for finding field direction around a straight current-carrying wire?
    Right-hand thumb rule
  6. Coil of many closely wound turns?
    Solenoid
  7. Temporary magnet produced using a current-carrying coil?
    Electromagnet
  8. Rule for finding force direction on a current-carrying conductor?
    Fleming’s left-hand rule
  9. Safety device that melts when excessive current flows?
    Fuse
  10. Safety wire connected to the earth?
    Earth wire
  11. Condition caused by an unintended low-resistance path with a sharp rise in current?
    Short circuit
  12. Medical imaging technique based on magnetic phenomena?
    MRI

Q. Exam Challenge Questions

1. A straight conductor carries current from north to south. If the current is reversed, what happens to the magnetic field direction?

Answer: The magnetic field direction reverses.

2. Why does a coil with 20 turns generally produce a stronger field than a similar single-turn loop carrying the same current?

Answer: The magnetic field contributions of the 20 turns add together, producing a stronger resultant field.

3. A student says, “Magnetic field lines can cross because they are imaginary.” Is the statement correct?

Answer: No. Even though they are imaginary representations, field lines cannot cross because the magnetic field at a given point has only one definite direction.

4. A conductor is placed in a magnetic field with current parallel to the field. Will the force be maximum?

Answer: No. The force is maximum when the current and magnetic field are perpendicular.

5. Why does reversing the poles of the magnet reverse the force on the current-carrying rod?

Answer: Reversing the poles reverses the magnetic field direction. Since force direction depends on the magnetic field direction, the force also reverses.

6. Why can an electromagnet be useful where a permanent magnet may not be suitable?

Answer: Its magnetic behaviour can be produced using current and can therefore be controlled by controlling the current.

7. A household appliance has a metallic body. Why should it be earthed?

Answer: Earthing provides a low-resistance path for leakage current and helps protect the user from severe electric shock.

8. What could happen if a fuse were replaced by an unsuitable thick conducting wire?

Answer: The protective function could be lost because the wire may not melt quickly enough when excessive current flows, increasing the risk of damage.

R. Rapid-Fire Revision Quiz

  1. Current produces what type of field?
    Magnetic field
  2. What detects magnetic direction?
    Compass
  3. Field lines outside a magnet: N → ?
    S
  4. Field lines inside a magnet: S → ?
    N
  5. Stronger field means field lines are more ______.
    Crowded
  6. Straight wire field lines are ______ circles.
    Concentric
  7. More current means ______ magnetic field.
    Stronger
  8. More distance means ______ magnetic field.
    Weaker
  9. Rule for magnetic field direction?
    Right-hand thumb rule
  10. Thumb shows?
    Current
  11. Fingers show?
    Magnetic field
  12. Many-turn cylindrical coil?
    Solenoid
  13. Solenoid resembles a ______ magnet.
    Bar
  14. Soft iron + solenoid + current gives?
    Electromagnet
  15. Current-carrying conductor in magnetic field experiences?
    Force
  16. Maximum force occurs at what angle?
    90°
  17. Rule for force direction?
    Fleming’s left-hand rule
  18. Left-hand thumb shows?
    Force/motion
  19. Household appliances are connected in?
    Parallel
  20. Safety wire?
    Earth wire
  21. Circuit protection device?
    Fuse
  22. Excessive current can melt the?
    Fuse
  23. Direct live-neutral contact can cause?
    Short circuit
  24. Too many appliances on one socket can cause?
    Overloading
  25. Medical application of magnetism?
    MRI

S. Important Questions for Exam Practice

  1. Explain how Oersted’s observation established a connection between electricity and magnetism.
  2. Define magnetic field and magnetic field lines.
  3. Write the important properties of magnetic field lines.
  4. Explain the magnetic field around a straight current-carrying conductor.
  5. State and explain the right-hand thumb rule.
  6. Explain how the magnetic field of a circular coil is produced.
  7. How does increasing the number of turns affect the field of a coil?
  8. Define a solenoid and describe its magnetic field.
  9. What is an electromagnet? How is it produced?
  10. Explain the force experienced by a current-carrying conductor in a magnetic field.
  11. State Fleming’s left-hand rule.
  12. Under what condition is the force on a current-carrying conductor maximum?
  13. Why does the direction of force reverse when current is reversed?
  14. Describe the arrangement of domestic electric circuits.
  15. Why are household appliances connected in parallel?
  16. What is the function of the earth wire?
  17. What is a fuse and how does it protect a circuit?
  18. Explain short circuiting.
  19. What is overloading? Give its causes.
  20. Explain the role of magnetism in MRI.