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JEE Mains · Physics · STD 12 - 11. Dual nature of radiation and matter
The kinetic energy of emitted electron is \(E\) when the light incident on the metal has wavelength \(\lambda\). To double the kinetic energy, the incident light must have wavelength.
- A \(\frac{ hc }{ E \lambda- hc }\)
- B \(\frac{ hc \lambda}{ E \lambda+ hc }\)
- C \(\frac{ h \lambda}{ E \lambda+ hc }\)
- D \(\frac{ hc \lambda}{ E \lambda- hc }\)
Answer & Solution
Correct Answer
(B) \(\frac{ hc \lambda}{ E \lambda+ hc }\)
Step-by-step Solution
Detailed explanation
\(E =\frac{ hc }{\lambda}-\phi-\text { (i) }\) \(2 E =\frac{ hc }{\lambda^{\prime}}-\phi-\) (ii) (ii) \(-\) (i) \(E = hc \left(\frac{1}{\lambda^{\prime}}-\frac{1}{\lambda}\right)\) \(\Rightarrow \lambda^{\prime}=\frac{ hc \lambda}{ E \lambda+ hc }\)
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