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प्रश्न
Is it always necessary to use red light to get a photoelectric effect?
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उत्तर
No, the broad wavelength and low energy of red light, photons do not have sufficient energy to pull an electron out of its orbital.
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संबंधित प्रश्न
What is the photoelectric effect?
Can microwaves be used in the experiment on photoelectric effect?
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 |
The threshold wavelength of tungsten is 2.76 x 10-5 cm.
(a) Explain why no photoelectrons are emitted when the wavelength is more than 2.76 x 10-5 cm.
(b) What will be the maximum kinetic energy of electrons ejected in each of the following cases
(i) if ultraviolet radiation of wavelength λ = 1.80 × 10-5 cm and
(ii) radiation of frequency 4 x 1015 Hz is made incident on the tungsten surface?
The electrons are emitted in the photoelectric effect from a metal surface.
The maximum kinetic energy of the photoelectrons depends only on ______
The minimum frequency for photoelectric effect on metal is 7 × 1014 Hz, Find the work function of the metal.
Explain the concept of the photoelectric effect.
State Einstein photoelectric equation.
With the help of a circuit diagram describing an experiment to study the photoelectric effect.
The maximum velocity of the photoelectron emitted by the metal surface is v. Charge and the mass of the photoelectron is denoted by e and m, respectively. The stopping potential in volt is ______.
When a photon enters glass from air, which one of the following quantity does not change?
Threshold frequency for a metal is 1015 Hz. Light of `lambda` = 4000 Å falls on its surface. Which of the following statements is correct?
A metal surface is illuminated by light of given intensity and frequency to cause photoemission. If the intensity of illumination is reduced to one-fourth of its original value then the maximum KE of the emitted photoelectrons would be ______.
Photoelectrons emitted from a metallic surface are initially ____________.
Threshold wavelength for lithium metal is 6250 Å. For photoemission, the wavelength of the incident light must be ______.
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 ______.
Following graphs show the variation of stopping potential corresponding to the frequency of incident radiation (F) for a given metal. The correct variation is shown in graph (v0 = Threshold frequency).
The work function of a photosensitive material is 4.0 eV. The longest wavelength of light that can cause photon emission from the substance is (approximately) ____________.
Two incident radiations having energies two times and ten times of the work function of a metal surface, produce photoelectric effect. The ratio of maximum velocities of emitted photo electrons respectively is ____________.
The ratio of slopes m1: ro2 of the lines given in the following graphs is, ______.
In a photoelectric experiment, ultraviolet light of wavelength 280 nm is used with a lithium cathode having work function Φ = 2.5 eV. If the wavelength of incident light is switched to 400 nm, find out the change in the stopping potential.
(h = 6.63 × 10-34 Js, c = 3 × 108 ms-1)
The radiation emitted, when an electron jumps from n = 3 to n = 2 orbit is a hydrogen atom, falls on a metal to produce photoelectron. The electrons from the metal surface with maximum kinetic energy are made to move perpendicular to a magnetic field of `1/320`T in a radius of 10-3m. Find the 320 work function of metal:
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.
We wish to observe an object which is 2.5Å in size. The minimum energy photon that can be used ______.
Light of wavelength λ, which is less than threshold wavelength is incident on a photosensitive material. If incident wavelength is decreased so that emitted photoelectrons are moving with same velocity, then stopping potential will ______.
If the maximum kinetic energy of emitted electrons in the photoelectric effect is 2eV, the stopping potential will be ______.
In a photoelectric experiment, the stopping potential is 1.5V. What is the maximum kinetic energy of a photoelectron?
