Home
Class 12
PHYSICS
a. A stopping potential of 0.82V is requ...

a. A stopping potential of `0.82V` is required to stop the emission of photoelectrons from the surface of a metal by light of eavelength `4000 A`. For light of wavelength `3000 A`, the stopping potential is `1.85V`. Find the value of Planck's constant. [1 electrons volt (eV)`=1.6xx10^(-19)J]`
b. At stopping potential, if the wavelength of the incident light is kept fixed at `4000 A`, but the intensity of light increases two times, will photoelectric current be botained ? Give reasons for your answer.

Text Solution

Verified by Experts

a. `(hc)/(lamda_1)=W+eV_1`.... (i)
`(hc)/(lamda_2)=W+eV_2` ...(ii)
Subtracting, we get
`(hc)/(lamda_2)-(hc)/(lamda_1)=e(eV_2-V_1)`
Here, `c=3xx10^8ms^(-1)`,
`lamda_1=4000A=4xx10^(-7)m`,`V_1=0.82V`
`lamda_2=3000A=3xx10^(-7)m`,`V_2=1.85V`
`hxx3xx10^8((1)/(3xx10^(-7))-(1)/(4xx10^(7)))`
`=1.6xx10^(-19)(1.85-0.82)`
or `hxx3xx10^(8)(1)/(12xx10^(-7))=1.6xx10^(-19)xx1.03`
Therefore, Planck's constant,
`h=(1.6xx10^(-19)xx1.03xx12xx10^(-7))/(3xx10^8)`
`=6.592xx10^(-34)J-s`
b. No, because stopping potential does not depend on intensity of incident light
Promotional Banner

Topper's Solved these Questions

  • PHOTOELECTRIC EFFECT

    CENGAGE PHYSICS|Exercise Exercise 3.1|15 Videos

  • PHOTOELECTRIC EFFECT

    CENGAGE PHYSICS|Exercise Exercise 3.2|8 Videos

  • PHOTOELECTRIC EFFECT

    CENGAGE PHYSICS|Exercise Integer Type|4 Videos

  • NUCLEI

    CENGAGE PHYSICS|Exercise QUESTION BANK|59 Videos

  • RAY OPTICS

    CENGAGE PHYSICS|Exercise DPP 1.6|12 Videos

Similar Questions

Explore conceptually related problems

In a photoelectric experiment the stopping potential for the incident light of wavelength 4000Å is 2 volt. If the wavelength be changed to 3000 Å, the stopping potential will be

If in a photoelectric cell , the wavelength of incident light is changed from 4000 Å to 3000 Å then change in stopping potential will be

The stopping potential for electrons emitted from a photosensitive surface illuminated by light of wavelength 491 nm is 0.710 V. When the incident wavelength is changed to a new value, the stopping potential is 1.43 V. The new wavelength is :

In a photoelectric cell, the wavelength of incident light is chaged from 4000A to 3600A . The change in stopping potential will be

The kinetic energies of the photoelectrons ejected from a metal surface by light of wavelength 2000 Å range from zero to 3.2 xx 10^(-19) Joule. Then find the stopping potential (in V).

In photoelectric effect experiment, the stopping potential for incident light of wavelength 4000 Å, is 3V. If the wavelength is changed to 2500 Å, the stopping potential will be

Metal surface emits photoelectrons when light of wavelength 400 nm is incident on it. Calculate the work function of the metal if stopping potential is 0.5 V.

The kinetic energies of photoelectrons range from zero to 4.0xx10^(-19)J when light of wavelength 3000 Å falls on a surface. What is the stopping potential for this light?