How is brightness measured and can I get a hint for this question? 5.2 Universal
ID: 3307892 • Letter: H
Question
How is brightness measured and can I get a hint for this question?5.2 Universal Behavior Consider data from a series of photoelectric experiments on a single sample, where the photocurrent the light source. v of Why, for fixed values of V and v, are we guaranteed that I(V, B,v)/B always gives the same value regardless of B? Would you expect this to break down at extremely low illuminations? If so, how? Would you expect this to break down at extremely high illuminations? If so, how? If we increase the energy of the photons and increase the retarding potential by the corresponding amount, why do we not get the same current?
Explanation / Answer
1) if frequency is greater than the throshold frequency then photoeletric current is directly proportional to the intensity of the light is B .Hence the ratio will be constant. But below threshold frequency is extremely low illuminance there is now photoelectric current however the intensity B may be. At high frequnecy photoelectric current (I)/Intensity(B) is no longer constant there will be more current than the expected value.
2) If we increase the retarding potential and energy of the photons than maximum kinetic energy of the electrons increases but no of electrons remains constant and due to increase potential the electrons cant reach at anode easily that's why current get reduced.