🧲 Magnetic Effects of Electric Current – MCQs (Class 10 Science, NCERT)

🔹 Part 2: Questions 26–50

Q26. The strength of magnetic field around a straight current-carrying conductor increases when:

A) Current decreases
B) Distance from conductor increases
C) Current increases
D) Length of conductor increases

Correct Answer: C) Current increases

Explanation:

• A) Decrease in current → Weak field.
• B) Further distance → Weak field.
• ✅ C) Field ∝ Current.
• D) Length doesn’t affect field at a point.

Q27. The pattern of magnetic field lines around a current-carrying straight conductor can be shown using:

A) Bar magnet
B) Iron filings
C) Compass needle
D) Both B and C

Correct Answer: D) Both B and C

Explanation:

• B) Iron filings → Show circular pattern.
• C) Compass → Shows tangent direction.
• ✅ D) Both are used in experiments.

Q28. The field inside a solenoid carrying current resembles that of:

A) Straight conductor
B) Circular coil
C) Bar magnet
D) Horseshoe magnet

Correct Answer: C) Bar magnet

Explanation:

• ✅ C) Solenoid behaves like a bar magnet with N & S poles.

Q29. Which pole of a solenoid is determined by Right-hand thumb rule?

A) North pole
B) South pole
C) Both poles
D) No pole

Correct Answer: A) North pole

Explanation:

• ✅ A) Curl fingers → Current; Thumb → North pole of solenoid.

Q30. The magnetic field strength of a solenoid can be increased by:

A) Increasing current
B) Increasing number of turns
C) Inserting soft iron core
D) All of these

Correct Answer: D) All of these

Explanation:

• ✅ D) All factors enhance solenoid’s field strength.

Q31. The device that produces large magnetic field using current is:

A) Solenoid
B) Motor
C) Generator
D) Transformer

Correct Answer: A) Solenoid

Explanation:

• ✅ A) Long coil of wire → Strong uniform field inside.

Q32. The magnetic field produced by a current-carrying circular loop is strongest at:

A) Outside loop
B) At the centre
C) At the edges
D) Along tangent

Correct Answer: B) At the centre

Explanation:

• ✅ B) Field lines are dense at centre.

Q33. The principle of electric motor is:

A) Magnetic effect of current
B) Heating effect of current
C) Electromagnetic induction
D) Electrolysis

Correct Answer: A) Magnetic effect of current

Explanation:

• ✅ A) Force on current-carrying conductor in magnetic field.

Q34. A current-carrying coil of wire behaves like:

A) Solenoid
B) Bar magnet
C) Generator
D) Transformer

Correct Answer: B) Bar magnet

Explanation:

• ✅ B) Loop behaves like tiny magnet.

Q35. The rule that gives direction of induced current is:

A) Fleming’s left-hand rule
B) Fleming’s right-hand rule
C) Ampere’s law
D) Ohm’s law

Correct Answer: B) Fleming’s right-hand rule

Explanation:

• ✅ B) Thumb = motion, First finger = field, Second = current.

Q36. A current-carrying conductor experiences no force in a magnetic field if:

A) Current is zero
B) Conductor parallel to field
C) Conductor perpendicular to field
D) Field is very strong

Correct Answer: B) Conductor parallel to field

Explanation:

• ✅ B) Force = BIL sinθ → Zero at θ = 0° (parallel).

Q37. A coil of many turns of insulated copper wire wound on a soft iron core is called:

A) Transformer
B) Electromagnet
C) Solenoid
D) Inductor

Correct Answer: B) Electromagnet

Explanation:

• ✅ B) Soft iron core inside solenoid forms electromagnet.

Q38. The strength of electromagnet depends on:

A) Current
B) Number of turns
C) Core material
D) All of these

Correct Answer: D) All of these

Explanation:

• ✅ D) All factors influence electromagnet strength.

Q39. The function of brushes in an electric motor is to:

A) Change direction of current
B) Provide contact between coil and battery
C) Reverse magnetic field
D) Reduce resistance

Correct Answer: B) Provide contact between coil and battery

Explanation:

• ✅ B) Brushes connect commutator with external circuit.

Q40. The function of split ring in motor is to:

A) Increase speed
B) Reverse current direction every half turn
C) Produce magnetic field
D) Reduce heating

Correct Answer: B) Reverse current direction every half turn

Explanation:

• ✅ B) Ensures continuous rotation in one direction.

Q41. Which law is the basis of electromagnetic induction?

A) Faraday’s law
B) Lenz’s law
C) Ohm’s law
D) Coulomb’s law

Correct Answer: A) Faraday’s law

Explanation:

• ✅ A) Change in magnetic flux → Induced emf.

Q42. The direction of induced current opposes the cause of its production. This is:

A) Ohm’s law
B) Lenz’s law
C) Fleming’s rule
D) Ampere’s law

Correct Answer: B) Lenz’s law

Explanation:

• ✅ B) Opposition principle → Conservation of energy.

Q43. In an electric generator, mechanical energy is converted into:

A) Chemical energy
B) Electrical energy
C) Heat energy
D) Light energy

Correct Answer: B) Electrical energy

Explanation:

• ✅ B) Generator works on electromagnetic induction.

Q44. The device which works on the principle of electromagnetic induction is:

A) Electric motor
B) Electric generator
C) Fuse
D) Battery

Correct Answer: B) Electric generator

Explanation:

• ✅ B) Generator uses changing flux → induced emf.

Q45. In DC motor, current is supplied through:

A) Slip rings
B) Split rings
C) Brushes only
D) Commutator

Correct Answer: B) Split rings

Explanation:

• ✅ B) Split rings reverse current for continuous motion.

Q46. In AC generator, coil ends are connected to:

A) Slip rings
B) Split rings
C) Brushes only
D) Fuse

Correct Answer: A) Slip rings

Explanation:

• ✅ A) Slip rings maintain alternating current output.

Q47. Which of the following devices does NOT work on magnetic effect of current?

A) Electric bell
B) Electric motor
C) Generator
D) Electric heater

Correct Answer: D) Electric heater

Explanation:

• ✅ D) Heater works on heating effect, not magnetic effect.

Q48. The frequency of AC in India is:

A) 100 Hz
B) 60 Hz
C) 50 Hz
D) 25 Hz

Correct Answer: C) 50 Hz

Explanation:

• ✅ C) Standard supply in India = 220 V, 50 Hz.

Q49. The potential difference between live and neutral wire in India is:

A) 110 V
B) 220 V
C) 440 V
D) 1000 V

Correct Answer: B) 220 V

Explanation:

• ✅ B) Domestic supply in India = 220 V.

Q50. The green wire in domestic circuit is the:

A) Live wire
B) Neutral wire
C) Earth wire
D) Fuse wire

Correct Answer: C) Earth wire

Explanation:

• ✅ C) Earth wire prevents shock by connecting appliances to ground.

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