The material that is not photo sensitive to visible light is
- caesium
- sodium
- rubidium
- cadmium
- potassium
The Correct Option is D
Approach Solution - 1
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
Approach Solution -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
Top Questions on Photoelectric Effect
- The cut-off voltage \( V_0 \) versus frequency \( \nu \) of the incident light curve is a straight line with a slope of \( \frac{h}{e} \). Explain this observation.
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- Explain the following observations using Einstein’s photoelectric equation:
(a) Photoelectric emission does not occur from a surface when the frequency of the light incident on it is less than a certain minimum value.
(b) It is the frequency, and not the intensity of the incident light which affects the maximum kinetic energy of the photoelectrons.
(c) The cut-off voltage \( V_0 \) versus frequency \( \nu \) of the incident light curve is a straight line with a slope \( \frac{h}{e} \).
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- Two statements are given, one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer from the codes (A), (B), (C), and (D) as given below.
Assertion (A): For monochromatic incident radiation, the emitted photoelectrons from a given metal have speed ranging from zero to a certain maximum value.
Reason (R): Each metal has a definite work function.
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- The threshold frequency for a given metal is \( 3.6 \times 10^{14} \) Hz. If monochromatic radiations of frequency \( 6.8 \times 10^{14} \) Hz are incident on this metal, find the cut-off potential for the photoelectrons.
Given: - Threshold frequency, \( \nu_0 = 3.6 \times 10^{14} \) Hz
- Frequency of incident radiation, \( \nu = 6.8 \times 10^{14} \) Hz
- Planck's constant, \( h = 6.63 \times 10^{-34} \, \text{J} \cdot \text{s} \)
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Einstein's Explanation of the Photoelectric Effect:
Einstein explained the photoelectric effect on the basis of Planck’s quantum theory, where light travels in the form of small bundles of energy called photons.
The energy of each photon is hν, where:- ν is the frequency of the incident light
- h is Planck’s constant
The number of photons in a beam of light determines the intensity of the incident light.When a photon strikes a metal surface, it transfers its total energy hν to a free electron in the metal.A part of this energy is used to eject the electron from the metal, and this required energy is called the work function.The remaining energy is carried by the ejected electron as its kinetic energy.
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