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NEETPhysicsDual Nature of Matter

In a photoelectric experiment, the macroscopic intensity of the incident light (measured in W/m ^2 ) is kept strictly constant. If the wavelength of the incident light is continuously decreased (while remaining below the threshold wavelength), how will the magnitude of the stopping potential and the saturation photocurrent change?

Options

  1. ABoth the magnitude of stopping potential and the saturation photocurrent increase.
  2. BThe magnitude of stopping potential increases, while the saturation photocurrent remains constant.
  3. CThe magnitude of stopping potential increases, while the saturation photocurrent decreases.
  4. DThe magnitude of stopping potential decreases, while the saturation photocurrent increases.

Correct answer

C. The magnitude of stopping potential increases, while the saturation photocurrent decreases.

Step-by-step solution

The magnitude of the stopping potential |V| is given by e|V| = hc - . As the wavelength decreases, the energy of each incident photon increases, which causes the stopping potential to increase. The macroscopic intensity of light is the total energy incident per unit area per unit time, given by I = n h c A , where n is the number of photons incident per second. Since the macroscopic intensity I is kept constant and is decreased, the energy per photon ( hc ) increases. To maintain a constant total energy per second,

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