Question

The maximum kinetic energy of photoelectrons coming out of a metal surface is \(10 \, \text{eV}\). The minimum voltage required to stop the emission of electrons from this metal surface is:

• A. \(10 \, V\)
• B. \(5 \, V\)
• C. \(-5 \, V\)
• D. \(-10 \, V\)

Hint:

Stopping potential is always negative because it opposes electron motion.

Answer 1

The Correct Option is D

Concept: Stopping potential is related to maximum kinetic energy: \[ K_{\max} = eV_0 \]

Step 1: Given data.
\[ K_{\max} = 10 \, \text{eV} \]

Step 2: Relation.
\[ V_0 = \frac{K_{\max}}{e} = 10 \, V \]

Step 3: Sign convention.
Stopping potential is negative (retarding potential). \[ \therefore V_0 = -10 \, V \]