On a photosensitive material, when frequency of incident radiation is increased by \(20 \%\), maximum kinetic energy of emitted photoelectrons increases from 0.4 eV to 0.7 eV . The work function of the material is
On a photosensitive material, when frequency of incident radiation is increased by \(20 \%\), maximum kinetic energy of emitted photoelectrons increases from 0.4 eV to 0.7 eV . The work function of the material is
Show Hint
- 3.5 eV
- 1.1 eV
- 0.48 eV
- 0.22 eV
The Correct Option is B
Solution and Explanation
Einstein's equation is \( K_{max}=hf-\phi \). The frequency rises by \( 20\% \), so the new photon energy is \( 1.2\,hf \).
Step 2: Two Equations
\( hf-\phi=0.4 \text{ eV} \)
\( 1.2hf-\phi=0.7 \text{ eV} \)
Step 3: Subtract
\( 0.2\,hf=0.3 \text{ eV} \), so \( hf=1.5 \text{ eV} \).
Step 4: Work Function
\( \phi=1.5-0.4=1.1 \text{ eV} \), option (B).
Final Answer:
The work function of the material is 1.1 eV. \[ \boxed{\text{(B) }\text{1.1 eV}} \]
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