Define the photoelectric effect. Write the laws of the photoelectric effect.

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The phenomenon of the emission of electrons from the metal surface exposed to light energy of suitable frequency is known as the Photoelectric effect.

The emitted electrons are called Photoelectrons.
The current produced due to these photoelectrons is called Photoelectric current.
Alkali metals like lithium, potassium, cesium, sodium, etc. show a photoelectric effect with visible light.
While, metals like cadmium, zinc, magnesium, etc. are sensitive to only ultraviolet light.

The laws of the photoelectric effect are:

For a given photosensitive material, there exists a certain minimum cut-off frequency, called the threshold frequency of the incident radiation below which no emission takes place irrespective of the intensity of incident radiation.
As the frequency of the incident radiation increases, the maximum kinetic energy or equivalent stopping potential of the emitted photoelectrons increases linearly, provided that the frequency of incident radiation is greater than the threshold frequency.
The photoelectric current is directly proportional to the intensity of incident radiation for a given photosensitive material and the frequency of incident radiation, provided that the frequency of incident radiation is greater than the threshold frequency.
For a given photosensitive material, the Saturation current is found to be proportional to the intensity of incident radiation whereas the stopping potential is independent of its intensity.
Photoelectric emission is an instantaneous process. The time lag is very small between the incidence of radiation and emission of photoelectrons (≅ 10^-9s or less), even when the incident radiation is very dim.

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Define the photoelectric effect. Write the laws of the photoelectric effect.

CBSE CLASS XII Related Questions

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3.Consider the nuclear reaction \( X \to Y + Z \). Let \( M_x \), \( M_y \), and \( M_z \) be the masses of the three nuclei X, Y, and Z respectively. Then which of the following relations hold true?

4.A rectangular loop of size 5 cm $\times$ 8 cm is lying in the $x$-$y$ plane in a uniform magnetic field $\vec{B} = (2.0\ \text{T})\hat{k}$. The total magnetic flux linked with the loop is:

5.A current of \(4.0\,\text{A}\) flows through a wire of length \(1\,\text{m}\) and cross-sectional area \(1.0\,\text{mm}^2\), when a potential difference of \(2\,\text{V}\) is applied across its ends. Calculate the resistivity of the material of the wire.

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1.
Two point charges -Q and Q are located at points (d, 0) and (0, d) respectively, in x-y plane. The electric field E at the origin will be:

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