Q. Which of the following correctly defines the photoelectric effect?
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[A] Light is made of electrons and when it hits on metal surface photons are emitted from the surface

[B] Light is made of photons and when it hits on metal surface electrons are emitted from the surface

[C] Light is made of protons and electrons and it goes under refraction when it hits metal surface

[D] Light is made of protons and electrons and it gets blocked when it hits on metal surface

Answer: B
Notes:

About Photoelectric effect: 

  • Light is made of photon and when it hits on metal surface electrons are emitted from the surface. This phenomenon is known as the photoelectric effect 
  • The emitted electrons are called photoelectrons 
  • The three laws of the photoelectric effect are as follows;
    1) The emission of electrons from the surface stops after a certain frequency known as the threshold frequency.
    2) The number of electrons that are emitted from the surface is directly proportional to the intensity of the incident light.
    3) Kinetic energy of the emitted electrons depends on the frequency of the incident light and is independent of its intensity. 

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