Question

Light of wavelength '\(λ\)' which is less than threshold wavelength is incident on a photosensitive material. If incident wavelength is decreased so that emitted photoelectrons are moving with some velocity then stopping potential

• A. becomes half
• B. increases
• C. decreases
• D. is zero

Hint:

Shorter wavelength means higher photon energy and higher V0.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Einstein's photoelectric equation is \(h\nu=\phi+K_{max}\), and the stopping potential \(V_0\) satisfies \(eV_0=K_{max}\).

Step 2: Effect of smaller wavelength:
Decreasing \(\lambda\) increases the frequency \(\nu=\dfrac c\lambda\), so the photon energy \(h\nu\) increases. The work function \(\phi\) is fixed.

Step 3: Result:
So \(K_{max}=h\nu-\phi\) increases, and \(V_0=\dfrac{K_{max}}e\) increases. Option (B).

Final Answer:
The stopping potential increases. \[ \boxed{B:\ \text{increases}} \]