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Dual Nature of Radiation and Matter

Multiple Choice Questions

201.

Find the correct statement(s) about photoelectric effect.

There is no significant time delay between the absorption of a suitable radiation and the emission of electrons.
Einstein analysis gives a threshold frequency above which no electron can be emitted
The maximum kinetic energy of the emitted photoelectrons is proportional to the frequency of incident radiation.
The maximum kinetic energy of electrons does not depend on the intensity of radiation.

202.

A photon of wavelength 300 nm interacts with a stationary hydrogen atom in ground state. During the interaction, whole energy of the photon is transferred to the electron of the atom. State which possibility is correct. (Consider, Plank constant =4 x 10^-15 eVs, velocity of light = 3 x 10m/s, ionisation energy of hydrogen = 13.6 eV)

Electron will be knocked out of the atom
Electron will go to any excited state of the atom
Electron will go only to first excited state of the atom
Electron will keep orbiting in the ground state of the atom

203.
The work function of metals is in the range of 2eV to 5eV. Find which of the following wavelength of light cannot be used for photoelectric effect? (Consider, Plank
constant = 4 x 10^-15 eVs, velocity of light = 3 x 10⁸ m/s)

510 nm

650 nm

400 nm

570 nm

650 nm

$Given that, 2 eV \leq ϕ \leq 5 eV$

Wavelength corresponding to minimum and maximum values of work function are

$λ_{\max} = \frac{hc}{E} = \frac{4 \times 10^{- 15} \times 3 \times 10^{8}}{2} = 6 \times 10^{- 7} m = 600 nm and λ_{\min} = \frac{hc}{E} = \frac{4 \times 10^{- 15} \times 3 \times 10^{8}}{5} = 2.4 \times 10^{- 7} m = 240 nm Clearly, wavelength range would be 240 \leq λ \leq 600$

Thus, wavelength 650 nm is not suitable for photoelectric effect.

Previous Year Papers

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Multiple Choice Questions

203. The work function of metals is in the range of 2eV to 5eV. Find which of the following wavelength of light cannot be used for photoelectric effect? (Consider, Plankconstant = 4 x 10-15 eVs, velocity of light = 3 x 108 m/s) 510 nm 650 nm 400 nm 570 nm

203.
The work function of metals is in the range of 2eV to 5eV. Find which of the following wavelength of light cannot be used for photoelectric effect? (Consider, Plank
constant = 4 x 10^-15 eVs, velocity of light = 3 x 10⁸ m/s)

510 nm

650 nm

400 nm

570 nm