Question

When a light of wavelength '\(λ\)' falls on the emitter of a photosensitive surface, maximum speed of emitted photoelectrons is 'V'. If the incident wavelength is changed to '\(2λ/3\)', maximum speed of emitted photoelectrons will be

• A. less than \(V(1.5)^{\frac{1}{2}}\)
• B. greater than \(V(1.5)^{\frac{1}{2}}\)
• C. less than \(V\)
• D. less than \(\frac{V}{2}\)

Hint:

Use Einstein photoelectric equation and keep the work function in the equation.

Answer 1

The Correct Option is B

Step 1: Ratio of KE
$\frac{K'}{K} = \frac{1.5E - \phi}{E-\phi}$ where $E = \frac{hc}\lambda$.

Step 2: Inequality
Since $\phi>0$, $\frac{1.5E-\phi}{E-\phi} > 1.5$, so $V'>V\sqrt{1.5}$. Option (B).

Final Answer:
Greater than V(1.5)^(1/2). \[ \boxed{\text{(B)}\ \text{greater than }V(1.5)^{1/2}} \]