The photoelectric effect is the ejection of electrons from the surface of a metal when
Correct answer: C. radiation of suitable wavelength falls on it
- A. it is heated to a high temperature
- B. electrons of suitable velocity strike it
- C. radiation of suitable wavelength falls on it
- D. it is placed in a strong electric field
Explanation
The photoelectric effect occurs when radiation of suitable wavelength (typically in the ultraviolet or higher energy range) falls on the surface of a metal, leading to the ejection of electrons.Incorrect Options and Explanations: (a) it is heated to a high temperature - This describes thermal emission, not the photoelectric effect. (b) electrons of suitable velocity strike it - The photoelectric effect is primarily dependent on the energy (wavelength) of incident radiation, not the velocity of electrons. (d) it is placed in a strong electric field - The photoelectric effect is primarily caused by incident radiation, not the application of an external electric field.
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About Electromagnetic Waves
Electromagnetic waves consist of mutually perpendicular, oscillating electric and magnetic fields that also remain perpendicular to the direction of propagation. They travel through vacuum at the speed of light and include radio waves, microwaves, infrared, visible, ultraviolet, X-rays and gamma rays. Unlike mechanical waves, they do not require a material medium.
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