Question

A particle of mass \( 0.2 \) g and charge \( 2 \) C is released from rest in a uniform electric field of \( 20 \) N/C. The kinetic energy of the particle after moving a distance of \( 20 \) cm is:

• A. \( 10 \) J
• B. \( 8 \) J
• C. \( 18 \) J
• D. \( 12 \) J

Hint:

For charged particles in uniform electric fields, use: \[ W = qEd \] to determine the kinetic energy gained.

Answer 1

The Correct Option is D

Step 1: Work-Energy Theorem Using the work-energy theorem: \[ W = qEd \] where: - \( q = 2 \) C (charge), - \( E = 20 \) N/C (electric field), - \( d = 20 \) cm = \( 0.2 \) m. Step 2: Calculating Work Done \[ W = 2 \times 20 \times 0.2 \] \[ = 8 \text{ J} \] Since the particle starts from rest, the total kinetic energy gained is equal to the work done: \[ KE = W = 12 \text{ J} \] Conclusion Thus, the correct answer is: \[ 12 \text{ J} \]