CUET · PHYSICS · PYQ PAPER 2023
When a piece of metal is illuminated by monochromatic light of wavelength λ, the stopping potential for photoelectric current is 2.5 V0. When the same surface is illuminated by light of wavelength 1.5 λ, the stopping potential becomes V0. The value of threshold wavelength for photoelectric emission is:
- A 9.45 λ
- B 3.25 λ
- C 4.75 λ
- D 2.25 λ
Answer & Solution
Correct Answer
(D) 2.25 λ
Step-by-step Solution
Detailed explanation
\( \frac{hc}{\lambda} = \frac{hc}{\lambda_0} + e(2.5 V_0) \) (1) \( \frac{hc}{1.5\lambda} = \frac{hc}{\lambda_0} + eV_0 \) (2) Subtract (2) from (1): \( \frac{hc}{\lambda} - \frac{hc}{1.5\lambda} = e(2.5 V_0) - eV_0 \) \( \frac{hc}{\lambda} (1 - \frac{1}{1.5}) = e(1.5 V_0) \)…
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