Verified answer

Answer:

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B) ultraviolet

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Answer:

In a photocell using cesium (caesium) as the material for the cathode, electrons are emitted when exposed to ultraviolet (UV) light. The phenomenon is known as the photoelectric effect. When photons of sufficiently high energy (such as ultraviolet photons) strike the cathode, they can liberate electrons from the surface of the material.

So, the correct answer is:

B) ultraviolet

Explanation: