10th class Physics, Chapter 17: Electromagnetism MCQs

1. Which statement is true about the magnetic poles?

1. (A) Unlike poles repel
2. (B) Like poles attract
3. (C) Magnetic poles do not affect each other
4. (D) A single magnetic pole does not exist ✓

2. A D.C motor converts:

1. (A) mechanical energy into electrical energy
2. (B) mechanical energy into chemical energy
3. (C) electrical energy into mechanical energy ✓
4. (D) electrical energy into chemical energy

3. The part of a D.C motor that reverses the direction of current through the coil every half-cycle:

1. (A) the armature
2. (B) the commutator ✓
3. (C) the brushes
4. (D) the split rings

4. The two main layers of the Earth's core that contribute to the generation of the magnetic field are:

1. (A) crust and mantle
2. (B) inner core and outer core ✓
3. (C) lithosphere and asthenosphere
4. (D) troposphere and stratosphere

5. What does a steady electric current in a conductor generate around it?

1. (A) Electric field
2. (B) Light
3. (C) Magnetic field ✓
4. (D) Sound waves

6. What happens to the magnetic field direction when the direction of the current is reversed?

1. (A) The magnetic field remains unchanged
2. (B) The magnetic field also reverses direction ✓
3. (C) The magnetic field becomes stronger
4. (D) The magnetic field disappears

7. The magnetic effect of electric current was discovered by:

1. (A) Michael Faraday
2. (B) Charles Coulomb
3. (C) George Ohm
4. (D) Hans Christian Oersted ✓

8. The magnetic field lines around a straight current-carrying wire are:

1. (A) straight lines parallel to the wire
2. (B) straight lines away from the wire
3. (C) ellipses
4. (D) concentric circles ✓

9. The magnetic field of a straight current-carrying wire is strongest:

1. (A) near the wire ✓
2. (B) far from the wire
3. (C) at the same value everywhere
4. (D) at the centre of the wire

10. In the right-hand grip rule for a straight wire, the thumb points in the direction of:

1. (A) the magnetic field
2. (B) the force
3. (C) the motion
4. (D) the current ✓

11. In the right-hand grip rule for a straight wire, the curled fingers show the direction of:

1. (A) the motion of the wire
2. (B) the magnetic field ✓
3. (C) the current
4. (D) the force

12. A current-carrying solenoid behaves like:

1. (A) a resistor
2. (B) a bar magnet ✓
3. (C) a charged rod
4. (D) a battery

13. In the right-hand rule for a solenoid, the thumb points towards:

1. (A) the centre of the solenoid
2. (B) the north pole ✓
3. (C) the south pole
4. (D) the direction of the current

14. Magnetic field lines outside a magnet go from:

1. (A) north pole to south pole ✓
2. (B) south pole to north pole
3. (C) north pole to north pole
4. (D) south pole to south pole

15. Closely spaced magnetic field lines show a:

1. (A) strong field ✓
2. (B) weak field
3. (C) zero field
4. (D) uniform weak field

16. Magnetic field lines:

1. (A) are real lines
2. (B) start and end at the same pole
3. (C) never cross each other ✓
4. (D) cross at the poles

17. Two parallel wires carrying currents in the same direction:

1. (A) repel each other
2. (B) do not affect each other
3. (C) rotate
4. (D) attract each other ✓

18. Two parallel wires carrying currents in opposite directions:

1. (A) attract and repel alternately
2. (B) repel each other ✓
3. (C) attract each other
4. (D) do not affect each other

19. The force on a current-carrying conductor in a magnetic field is given by:

1. (A) F = I² R
2. (B) F = I L B sin θ ✓
3. (C) F = I L / B
4. (D) F = B / I L

20. The force on a current-carrying conductor in a magnetic field is always:

1. (A) parallel to the field
2. (B) parallel to the current
3. (C) in the direction of the current
4. (D) at right angles to both the field and the current ✓