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NEETPhysicsDual Nature of Matter

In a photoelectric experiment, a student plots the saturation photocurrent ( I ) and the magnitude of the stopping potential ( |V| ) as functions of time ( t ). The graph of I versus t is a horizontal straight line with a positive intercept, while the graph of |V| versus t is a straight line with a positive slope. Based on these observations, which of the following statements about the incident light source is correc

Options

  1. AThe power of the source is constant, and its frequency is increasing.
  2. BThe source emits a constant number of photons per second, and its total power is increasing.
  3. CThe frequency of the source is constant, and its intensity is increasing.
  4. DThe wavelength of the incident light is increasing, and its intensity is constant.

Correct answer

B. The source emits a constant number of photons per second, and its total power is increasing.

Step-by-step solution

The saturation photocurrent I depends directly on the number of incident photons per unit time ( n ). Since the graph of I versus t is a horizontal line, I is constant, which means n is constant. The stopping potential |V| is given by Einstein's photoelectric equation e|V| = h - . Since the graph of |V| versus t has a positive slope, |V| is increasing over time, which implies the frequency of the incident light is increasing. The total power of the incident light is P = n h . Since n is constant and is increasing,

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