Concepts Of Physics MCQ Edition [Volume 2]PhysicsPhotoelectric Effect and Wave–Particle Duality
A point source induces the photoelectric effect on a small metal plate. Which of the curves shown could depict the saturation photocurrent as a function of the distance between the source and the metal?
Options
- Ad
- Ba
- Cb
- Dc
Correct answer
A. d
Step-by-step solution
The saturation photocurrent i is directly proportional to the intensity I of the incident light on the metal plate. For a point source of light, the intensity I at a distance r is given by I = P 4 r^2 , where P is the power of the source. Thus, the intensity is inversely proportional to the square of the distance, i.e., I 1 r^2 . Therefore, the saturation photocurrent i is also inversely proportional to the square of the distance: i 1 r^2 The graph of i versus r will be a curve that decreases with distance and is c