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

🔹 Part 1: Questions 1–25

Q1. The magnetic field around a current-carrying straight conductor is in the form of:

A) Straight lines
B) Circular lines
C) Elliptical lines
D) Parabolic lines

Correct Answer: B) Circular lines

Explanation:

• A) Straight lines → Incorrect, field lines curve around.
• ✅ B) Circular lines → Concentric circles around conductor (Right-hand thumb rule).
• C, D → Wrong geometrical shapes.

Q2. The direction of magnetic field produced by current in a conductor is given by:

A) Fleming’s left-hand rule
B) Right-hand thumb rule
C) Fleming’s right-hand rule
D) Ampere’s rule

Correct Answer: B) Right-hand thumb rule

Explanation:

• A) Left-hand → Force direction.
• ✅ B) Right-hand thumb → Thumb = current, curled fingers = field direction.
• C) Right-hand rule → For generators.
• D) Ampere’s law → Quantitative relation, not direction.

Q3. Magnetic field inside a solenoid carrying current is:

A) Zero
B) Strong and uniform
C) Weak and non-uniform
D) Negligible

Correct Answer: B) Strong and uniform

Explanation:

• ✅ B) Solenoid produces nearly uniform strong field inside.
• A, C, D → Incorrect.

Q4. The magnetic field lines inside a long straight solenoid are:

A) Curved
B) Parallel and straight
C) Diverging
D) Circular

Correct Answer: B) Parallel and straight

Explanation:

• ✅ B) Indicates uniform field inside solenoid.

Q5. The region around a magnet where its effect can be felt is called:

A) Magnetic pole
B) Magnetic field
C) Magnetic domain
D) Flux

Correct Answer: B) Magnetic field

Explanation:

• ✅ B) Defined as region where magnetic force is felt.

Q6. A current-carrying conductor placed in a magnetic field experiences:

A) No force
B) Only electric force
C) Magnetic force
D) Gravitational force

Correct Answer: C) Magnetic force

Explanation:

• ✅ C) Lorentz force = q(v × B) → For charges, conductor → F = BIL.

Q7. The rule to determine the direction of force on current-carrying conductor is:

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

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

Explanation:

• ✅ B) Thumb = Force, First finger = Field, Second = Current.

Q8. An electric motor works on the principle of:

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

Correct Answer: B) Magnetic effect of current

Explanation:

• ✅ B) Motor → Force on current-carrying coil in magnetic field.

Q9. The field lines outside a bar magnet emerge from:

A) South pole
B) North pole
C) Both poles
D) Centre

Correct Answer: B) North pole

Explanation:

• ✅ B) By convention, field emerges from North and enters South.

Q10. The SI unit of magnetic field strength (B) is:

A) Tesla
B) Gauss
C) Weber
D) Newton

Correct Answer: A) Tesla

Explanation:

• ✅ A) 1 Tesla = 1 N/(A·m).
• B) Gauss → CGS unit.
• C, D → Wrong.

Q11. A soft iron core is used inside a solenoid to:

A) Increase resistance
B) Increase magnetic field strength
C) Reduce field strength
D) Act as insulator

Correct Answer: B) Increase magnetic field strength

Explanation:

• ✅ B) Soft iron increases flux density (acts as electromagnet).

Q12. The direction of induced current in a conductor is given by:

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

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

Explanation:

• ✅ C) Thumb = Motion, First finger = Field, Second = Current.

Q13. Electromagnetic induction is the process of:

A) Inducing current by heating
B) Inducing current by chemical reaction
C) Inducing current by changing magnetic field
D) Inducing charge by friction

Correct Answer: C) Inducing current by changing magnetic field

Explanation:

• ✅ C) Faraday’s law → Change in magnetic flux induces emf.

Q14. The device that converts electrical energy into mechanical energy is:

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

Correct Answer: B) Motor

Explanation:

• ✅ B) Motor works on magnetic effect of current.

Q15. The device that converts mechanical energy into electrical energy is:

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

Correct Answer: B) Generator

Explanation:

• ✅ B) Based on electromagnetic induction.

Q16. The shape of field lines around a straight current-carrying conductor is:

A) Straight lines
B) Circular concentric circles
C) Random lines
D) Parallel lines

Correct Answer: B) Circular concentric circles

Explanation:

• ✅ B) Around wire → Circular loops.

Q17. The north pole of Earth’s magnet is near:

A) Geographic north
B) Geographic south
C) Equator
D) Centre of Earth

Correct Answer: B) Geographic south

Explanation:

• ✅ B) Magnetic north near geographic south → explains compass.

Q18. The force on current-carrying conductor in magnetic field is maximum when angle between field and current is:

A) 0°
B) 45°
C) 90°
D) 180°

Correct Answer: C) 90°

Explanation:

• ✅ C) F = BIL sin θ → Maximum at 90°.

Q19. A galvanometer can be converted to ammeter by:

A) Putting high resistance in series
B) Putting low resistance in parallel
C) Putting high resistance in parallel
D) Putting low resistance in series

Correct Answer: B) Putting low resistance in parallel

Explanation:

• ✅ B) Shunt resistance bypasses excess current.

Q20. A galvanometer can be converted to voltmeter by:

A) Putting high resistance in series
B) Putting low resistance in parallel
C) Putting high resistance in parallel
D) Putting low resistance in series

Correct Answer: A) Putting high resistance in series

Explanation:

• ✅ A) High resistance limits current, measures voltage.

Q21. The device used to protect circuits from overloading is:

A) Motor
B) Generator
C) Fuse
D) Battery

Correct Answer: C) Fuse

Explanation:

• ✅ C) Fuse melts if current exceeds safe limit.

Q22. The strength of magnetic field inside solenoid depends on:

A) Number of turns per unit length
B) Current through solenoid
C) Nature of core material
D) All of these

Correct Answer: D) All of these

Explanation:

• ✅ D) All factors affect magnetic field strength.

Q23. In domestic circuits, the earth wire is used for:

A) Reducing power loss
B) Preventing short circuit
C) Preventing shock
D) Providing extra current

Correct Answer: C) Preventing shock

Explanation:

• ✅ C) Earth wire directs leakage current safely to ground.

Q24. Magnetic field due to a circular coil is strongest:

A) At its periphery
B) At its centre
C) Near ends
D) Outside coil

Correct Answer: B) At its centre

Explanation:

• ✅ B) Field lines are densest at centre of coil.

Q25. The SI unit of magnetic flux is:

A) Tesla
B) Weber
C) Gauss
D) Ampere

Correct Answer: B) Weber

Explanation:

• ✅ B) Flux unit = Weber (Wb).

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