Question

When orange light falls on a photosensitive surface the photocurrent begins to flow. Velocity of emitted electrons will be more when surface is hit by
A. Red light
B. Violet light
C. Thermal radiations
D. Radio waves

Answer 1

Hint:To answer this question, we first need to understand what is the formula of energy that is generated when a light falls which is (where is the frequency of the light). Einstein believed that a v-frequency light wave may be called a stream of photons. As this photon interacts with an electron, it gives the electron its whole energy in a one-to-one interaction, and the rest energy is used by the electron as KE.

Complete answer:
As we know that the energy released or the velocity of the emitted electrons will be more for the light wave with more frequency as suggested by the formula discussed above in the hint.As seen here in the options frequency of red light, thermal radiations and radio waves are less than that of

Orange light which means that the energy released by them is less than that of orange light.But violet light has more frequency than orange light. Therefore, energy release by violet light is more than that of orange light. Hence the velocity of emitted electrons is more when the surface is hit by violet light.

Therefore, the correct answer is option B.

Note: The electric current that flows through a photosensitive system, such as a photodiode, as a result of exposure to radiant power is known as photocurrent.Photocurrent may be caused by the photoelectric, photoemissive, or photovoltaic effects. Saturation current is the highest (maximum) value of the photo-current.