Advertisements
Advertisements
प्रश्न
The threshold wavelength of silver is 3800Å. Calculate the maximum kinetic energy in eV of photoelectrons emitted, when ultraviolet light of wavelength 2600Å falls on it.
(Planck’s constant, h =6.63 x 1O-34J.s.,
Velocity of light in air, c = 3 x 108 m / s)
Advertisements
उत्तर
Wavelength of silver, λ1 = 3800 Aº
Wavelength of ultraviolet light, λ2 = 2600 Aº
H = 6.63 × 10-34 Js
Velocity of light in air, c = 3 × 108 m/s
To calculate kinetic energy, K.E. = hv − hvº
`"K.E."="hc"[1/lambda-1/lambda_o]`
`"K.E."=19.89xx10^-19[1/2.6-1/3.8]`
`"K.E."=(2.416xx10^-19)/(1.6xx10^-19)`
K.E. = 1.51 eV
Hence, the maximum kinetic energy emitted by the photoelectron is 1.51 eV.
APPEARS IN
संबंधित प्रश्न
When radiations of wavelength λ1 and λ2 are incident on certain photosensitive, such that E1 > E2 . Then Planck's constant 'h' is ......................... .
(C = Velocity of light).
Find the wave number of a photon having energy of 2.072 eV
Given : Charge on electron = 1.6 x 10-19 C,
Velocity of light in air = 3 x 108 m/s,
Planck’s constant = 6.63 x 10-34 J-s.
State two important properties of photon which are used to write Einstein’s photoelectric equation.
Define (i) stopping potential and (ii) threshold frequency, using Einstein’s equation and drawing necessary plot between relevant quantities.
Write Einstein's photoelectric equation and mention which important features in photoelectric effect can be explained with the help of this equation.
The maximum kinetic energy of the photoelectrons gets doubled when the wavelength of light incident on the surface changes from λ1 to λ2. Derive the expressions for the threshold wavelength λ0 and work function for the metal surface.
Write its S.I. unit of (intensity of radiation)
Radiation of frequency 1015 Hz is incident on two photosensitive surface P and Q. There is no photoemission from surface P. Photoemission occurs from surface Q but photoelectrons have zero kinetic energy. Explain these observations and find the value of work function for surface Q.
The work function for a metal surface is 2.2eV. If the light of wavelength 5000Å is incident on the surface of the metal, find the threshold frequency and incident frequency. Will there be an emission of photoelectrons or not? (c = 3 x 108 m/ s, 1eV = 1.6x10-19 J , h = 6.63 x 10-34 J.s.)
Einstein's photoelectric equation is:
a) `E_"max" = hlambda - varphi_0`
b) `E_"max"= (hc)/lambda varphi_0`
c) `E_"max" = hv + varphi_0`
d) `E_"max" = (hv)/lambda + varphi_0`
With reference to the photoelectric effect, define threshold wavelength
According to Einstein’s model, the threshold frequency for a metal having work function ϕ0 is given by _________.
According to the Einstein’s model, stopping potential Vo for a metal having work function ϕ0 is given by ______.
Calculate the maximum kinetic energy of photoelectrons emitted by a metal (work function = 1.5 eV) when it is illuminated with light of wavelength 198 nm.
Plot a labelled graph of |Vs| where Vs is stopping potential versus frequency f of the incident radiation. State how will you use this graph to determine the value of Planck's constant?
A police van moving on a highway with a speed of 30 km/h fires a bullet at a thief's car speeding away in the same direction with a speed of 192 km/h. If the muzzle speed of the bullet is 150 m is, with what speed does the bullet hit the thief's car?
Radiations of two photon's energy, twice and ten times the work function of metal are incident on the metal surface successively. The ratio of maximum velocities of photoelectrons emitted in two cases is:
According to Einstein's photoelectric equation, the plot of the kinetic energy of the emitted photoelectrons from a metal Vs the frequency of the incident radiation gives as straight the whose slope:
Threshold frequency for photoelectric effect on sodium corresponds to a wave length 5000. Its work function is ______.
Who indirectly determined the mass of the electron by measuring the charge of the electrons?
The wavelength of matter is independent of
The moment of a photon is given by
- Calculate the energy and momentum of a photon in a monochromatic beam of wavelength 331.5 nm.
- How fast should a hydrogen atom travel in order to have the same momentum as that of the photon in part (a)?
- Calculate the frequency of a photon of energy 6.5 × 10−19 J.
- Can this photon cause the emission of an electron from the surface of Cs of work function 2.14 eV? If yes, what will be the maximum kinetic energy of the photoelectron?
How does stopping potential in photoelectric emission vary if the frequency of incident radiation decreases?
