Question

Consider the following statements:
Statement (A): The restoring couple in the moving coil galvanometer is due to the current in the coil.
Statement (B): Wires of magnetic field around a current carrying straight conductor will be circular in a plane parallel to the conductor.
Statement (C): When a charged particle enters a uniform magnetic field, its kinetic energy increases.

• A. A, B, C are true
• B. A, B true, C is false
• C. A, C true, B is false
• D. A, B, C are false

Hint:

In a moving coil galvanometer, the restoring torque comes from the spring or suspension, not the current. Magnetic field lines around a straight wire are perpendicular circles. Magnetic forces do no work on charged particles in uniform fields; kinetic energy remains constant.

Answer 1

The Correct Option is D

Step 1: Statement A evaluation.
The restoring couple in a moving coil galvanometer comes from the spring suspension, not from the current; the current generates the deflecting torque. Hence, Statement A is false.

Step 2: Statement B evaluation.
Magnetic field lines around a straight current-carrying wire form concentric circles in planes perpendicular to the wire, not parallel. Hence, Statement B is false.

Step 3: Statement C evaluation.
A charged particle moving perpendicular to a uniform B field has its velocity direction changed but speed unchanged; kinetic energy stays constant. Hence, Statement C is false.

Step 4: Overall conclusion.
All three statements are incorrect.