CBSE
Multiple Choice QuestionsAssertion: As work function of a material increases by some mechanism, it requires greater energy to excite the electrons from its surface.
Reason: A plot of stopping potential (Vs) versus frequency (v) for different metals, has greater slope for metals with greater work functions.
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
Light of two different frequencies whose photons
have energies 1 eV and 2.5 eV respectively, successively illuminate a metallic surface whose work function is 0.5 eV. Ratio of maximum speeds of emitted electrons will be
1 : 4
1 : 1
1 : 5
1 : 2
de-Broglie wavelength associated with a ball of mass 1 kg having kinetic energy 0.5 J is
6.63 × 10-30 m
6.63 × 10-34 m
1.32 × 10-33 m
1.32 × 10-34 m
Which of the following has the longest de Broglie wavelength if they are moving with the same velocity?
Neutron
Proton
-particle
β-particle
Work function of a metal is 5.2 x 10-18, then its threshold wavelength will be
736.7 Ao
760.7 Ao
301 Ao
344.4 Ao
Assertion: When a certain wavelength of light fall on a metal surface it ejects electron.
Reason: Light has wave nature.
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
The graph and stopping potential (V) of three metals having work function in an experiment of photoelectric effect is plotted as shown in the figure. Which one of the following statement is/are correct? [Here λ is the wavelength of the incident ray ]
(i) Ratio of work functions = 1 : 2 : 4
(ii) Ratio of work functions = 4 : 2 : 1
(iii) tanθ ∝ , where h = Planck's constant, c = speed of light
(iv)The violet colour-light can eject photoelectrons from metals 2 and 3
(i), (iii)
(i), (iv)
(ii), (iii)
(i), (ii) and (iv)
In photoelectric effect, the number of photo-electrons emitted is proportional to
velocity of incident beam
frequency of incident beam
intensity of incident beam
work function for cathode material
Photoelectric effect supports quantum nature of light because
there is minimum frequency of light below which no photoelectrons are emitted
the maximum energy of photoelectron depends only on the frequency of light and not on its intensity
photoelectric effect is an instantaneous process
all the above choices are correct
An isotropic point source emits light with wavelength 500 nm. The radiation power of the source is P = 10 W . Find the number of photons passing through unit area per second at a distance of 3 m from the source.
5.92 x 1017 / m2 s
2.23 x 1017 / m2 s
2.23 x 1018 /m2 s
5.92 x 1018 /m2 s
