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NEETPhysicsDual Nature of Matter

The work functions of two different photosensitive metals A and B are 2.0 ~eV and 5.0 ~eV respectively. The ratio of the longest wavelengths of light that can cause photoelectron emission from metal A to that from metal B is

Options

  1. A5 : 2
  2. B2 : 5
  3. C25 : 4
  4. D4 : 25

Correct answer

A. 5 : 2

Step-by-step solution

The longest wavelength of light that can cause photoelectric emission is the threshold wavelength ( ₀ ). The work function is related to the threshold wavelength by the equation: = hc ₀ This implies that the threshold wavelength is inversely proportional to the work function: ₀ 1 For metals A and B, the ratio of their threshold wavelengths is: _A _B = _B _A Given _A = 2.0 ~eV and _B = 5.0 ~eV : _A _B = 5.0 2.0 = 5 2 Thus, the required ratio is 5 : 2 . Answer: 5 : 2

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