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प्रश्न
What is the photoelectric effect?
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उत्तर
The phenomenon of the emission of electrons from a metal surface when electromagnetic radiation of the appropriate frequency is incident on it is known as the photoelectric effect.
संबंधित प्रश्न
Explain the inverse linear dependence of stopping potential on the incident wavelength in a photoelectric effect experiment.
Using the values of work function given in the following table, tell which metal will require the highest frequency of incident radiation to generate photocurrent.
Typical values of work function for some common metals
| Metal | Work function (in eV) |
| Potassium | 2.3 |
| Sodium | 2.4 |
| Calcium | 2.9 |
| Zinc | 3.6 |
| Silver | 4.3 |
| Aluminium | 4.3 |
| Tungsten | 4.5 |
| Copper | 4.7 |
| Nickel | 5.0 |
| Gold | 5.1 |
Given the following data for incident wavelength and the stopping potential obtained from an experiment on the photoelectric effect, estimate the value of Planck's constant and the work function of the cathode material. What is the threshold frequency and corresponding wavelength? What is the most likely metal used for emitter?
| Incident wavelength (in Å) | 2536 | 3650 |
| Stopping potential (in V) |
1.95 | 0.5 |
Draw a neat labelled diagram of a schematic of the experimental setup for the photoelectric effect.
What is the photoelectric effect? Define stopping potential and photoelectric work function.
State Einstein’s photoelectric equation. Explain all characteristics of the photoelectric effect, on the basis of Einstein’s photoelectric equation.
When a photon enters glass from air, which one of the following quantity does not change?
When light falls on a metal surface, the maximum kinetic energy of the emitted photoelectrons depends upon ______
For photoelectric emission from certain metal, the cut-off frequency is v. If radiation of frequency 2v impinges on the metal plate, the maximum possible velocity of the emitted electron will be (m is the electron mass) ____________.
An important spectral emission line has a wavelength of 21 cm. The corresponding photon energy is (h = 6.62 x 10-34 Js, c = 3 x 108 m/s) ____________.
When certain metal surface is illuminated with a light of wavelength A., the stopping potential is V, When the same surface is illuminated by light of wavelength 2λ, the stopping potential is `("V"/3)`. The threshold wavelength for the surface is ______.
When light of wavelength 'λ' is incident on a photosensitive surface, the stopping potential is 'V'. When light of wavelength '3λ' is incident on the same surface, the stopping potential is `"V"/6`. Threshold wavelength for the surface is _______.
Photoelectrons are emitted from a photosensitive surface for the light of wavelengths λ1 = 360 nm and λ2 = 600 nm. What is the ratio of work functions for lights of wavelength 'λ1' to 'λ2'?
When a surface 1 cm thick is illuminated by light of wavelength 'λ', the stopping potential is 'V0'. When the same surface is illuminated by light of wavelength '3λ', the stopping potential is `"V"_0/6`. The threshold wavelength for the metallic surface is ______.
When a certain metallic surface is illuminated with monochromatic light of wavelength '`lambda`', the stopping potential for photoelectric effect is '3V0'. If the same surface is illuminated with a light of wavelength '`2 lambda`', the stopping potential is found as 'V0'. The threshold wavelength for this surface is ____________.
When a photosensitive surface is irradiated by lights of wavelengths `lambda_1` and `lambda_2`, kinetic energies of emitted photoelectrons are E1 and E2 respectively. The work function of the photosensitive surface is ____________.
The stopping potential in the context of photoelectric effect depends on the following property of incident electromagnetic radiation ______.
The wavelength of light incident on a metal surface is reduced from 300 nm to 200 nm (both are less than threshold wavelength). What is the change in the stopping potential for photoelectrons emitted from the surface will be ______ V. (Take h = 6.6 × 10-34 J-s)
The maximum kinetic energy of the photoelectrons ejected will be ______ eV when the light of wavelength 350 nm is incident on a cesium surface. The work function of cesium = 1.9 eV.
A point isotropic light source of power P = 12 watts is located on the axis of a circular mirror of radius R = 3 cm. If the distance of the source from the centre of the mirror is a = 39 cm and the reflection coefficient of the mirror is α = 0.70 then the force exerted by the light ray on the mirror is ______ × 10-10 N.
On a photosensitive material when frequency of incident radiation is increased by 30%, kinetic energy of emitted photoelectrons increases from 0.4 eV. The work function of the surface is ______.
The following graphs show the variation of stopping potential corresponding to the frequency of incident radiation (ν) for a given metal. The correct variation is shown in graph [ν0 = threshold frequency].
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(A) |
(B) |
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(C) |
(D) |
Light of two different frequencies whose photons have energies 1.3 eV and 2.8 eV respectively, successfully illuminate a metallic surface whose work function is 0.8 eV. The ratio of maximum speeds of emitted electrons will be ______.
When monochromatic light of frequency v1 falls on a metal surface, the stopping potential required is found to be V1. If the radiation of frequency v2 is incident on the surface, the stopping potential required V2 is ______. (v2 > v1)
Explain the failure of wave theory of light to account for the observations from experiments on photoelectric effect.
Light of wavelength 'λ' falls on a metal having work function \[\frac {hc}{λ_0}\]. Photoelectric effect will take place only if (λ0 is the threshold wavelength) ______.
A parallel plate capacitor with air between the plates has capacitance 9 pF. The separation between the plates becomes thrice and the space between them is filled with a medium of dielectric constant 6. The capacitance becomes 'x' pF. The value of 'x' is ______.
