Question

The material that is not photo sensitive to visible light is

• A. caesium
• B. sodium
• C. rubidium
• D. cadmium
• E. potassium

Answer 1

The Correct Option is D

The photoelectric effect occurs when materials emit electrons when exposed to light. Certain materials are photo sensitive to visible light, and their work function determines the wavelength of light required to release electrons.
Caesium, sodium, rubidium, and potassium are photo sensitive to visible light due to their low work functions, allowing them to release electrons when exposed to visible light.
Cadmium, on the other hand, has a higher work function, meaning it is not photo sensitive to visible light and requires ultraviolet light for the photoelectric effect to occur.
Thus, cadmium is the material that is not photo sensitive to visible light.

The correct option is (D) : Cadmium

Answer 2

Photoelectric emission occurs when a material emits electrons upon absorbing light. For photoemission to occur with visible light, the material must have a low work function.
 
Alkali metals like caesium, sodium, rubidium, and potassium have low work functions and are photosensitive to visible light. 

However, cadmium is a transition metal with a relatively high work function, and it is not sensitive to visible light. Therefore, it does not show a photoelectric effect with visible light.

✅ Correct Option: cadmium