Test Questions

1. State the right-hand rule for determining the direction of the magnetic force on a moving charge.
2. A straight wire of length 0.5 m carries a current of 3 A in a magnetic field of 0.4 T at right angles. Find the force on the wire.
3. A proton moves at 1.2×10⁶ m/s in a 0.2 T magnetic field perpendicular to its velocity. Calculate the force acting on it.
4. Derive an expression for the induced EMF in a coil rotating in a uniform magnetic field.
5. A solenoid of 200 turns, length 0.5 m, and current 2 A is placed in a magnetic field. Calculate the magnetic field inside the solenoid.
6. State Faraday’s law and Lenz’s law, and explain how they are related.
7. A 0.25 m wire moves at 4 m/s in a 0.8 T magnetic field. Find the induced EMF and the induced current if resistance = 0.5 Ω.
8. Calculate the energy stored in a 2 H inductor carrying 4 A of current.
9. An RL circuit has R = 6 Ω, L = 3 H. Find its time constant and the current after 1 second when connected to a 12 V battery.
10. Explain qualitatively what happens when a magnet is dropped through a copper tube (no current source present).