CBSE
When light of wavelength 300 nm falls on a photoelectric emitter, photoelectrons are liberated. For another emitter, light of wavelength 600 nm is sufficient for liberating photoelectrons. The ratio of the work function of the two emitters is
1 : 2
2 : 1
4: 1
1: 4
The work function of a metal is 3.4 eV. If the frequency of incident radiation is increased to twice, then the work function of the metal becomes
3.4 eV
7.2 eV
6.8 eV
1.7 eV
Maximum velocity of photoelectron emitted is 4.8m/s. If e/m ratio of the electron is then stopping potential is given by
5 10-10 J/C
3 10-7 J/C
7 10-11 J/C
2.5 10-2 J/C
The de-Broglie wavelength of an electron having 80 eV of energy is nearly (1 eV = 1.6 × 10-19J, mass of electron = 9.1 × 10-31 kg, Planck's constant = 6.6 × 10-34 J-s)
140 Å
0.14 Å
14 Å
1.4 Å
Which of the following figures represents the variation of the particle momentum and associated de-Broglie wavelength?
If red light is replaced by white light then width of diffraction pattern will
increases
decreases
a central white band is obtained
no effect
Maximum velocity of the photoelectrons emitted by a metal surface is 1.2x106 ms-1. Assuming the specific charge of the electron to be 1.8 x1011 C kg-1, the value of the stopping potential in volt will be
2
3
4
6
In Planck's oscillator energy is given as
E = If K = 0, then energy would be
hν
0
Kt
∞
Assertion: On increasing the frequency of light larger number of photoelectrons are emitted.
Reason: The number of electrons emitted depends on the intensity of incident light.
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reasonn are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If assertion is false but reason is true.
Colour of star depends upon
luminosity
temperature
brightness
all of these