The time by a photoelectron to come out after the photon strikes is approximately

• 10⁻¹ s

• 10⁻⁴ s

• 10−¹⁰ s

• 10−¹⁰ s

An alpha nucleus of energy 1 /2 mv² bombards a heavy nuclear target of charge Ze. Then the distance of closest approach for the alpha nucleus will be proportional to 

• 1/Ze

• v²

• 1/m

• 1/m

If I₀ is the intensity of the principal maximum in the single slit diffraction pattern, then what will be its intensity when the slit width is doubled?

• 2I₀

• 4I₀

• I₀

• I₀

The maximum number of possible interference maxima for slit-separation equal to twice the wavelength in Young’s double-slit experiment is

• infinite

• five

• three

• three

15.

An electromagnetic wave of frequency ν = 3.0 MHz passes from vacuum into a dielectric medium with permittivity ε = 4.0. Then

• wavelength is doubled and the frequency remains unchanged

• wavelength is doubled and frequency becomes half

• wavelength is halved and frequency remains unchanged

• wavelength is halved and frequency remains unchanged

According to Einstein’s photoelectric equation, the plot of the kinetic energy of the emitted photo electrons from a metal Vs the frequency, of the incident radiation gives straight line whose slope

• depends on the nature of the metal used

• depends on the intensity of the radiation

• depends both on the intensity of the radiation and the metal used

• depends both on the intensity of the radiation and the metal used

The work function of a substance is 4.0 eV. Then longest wavelength of light that can cause photoelectron emission from this substance approximately

• 540 nm

• 400 nm

• 310 nm,

• 310 nm,

The angular width of the central maximum in a single slit diffraction pattern is 60°. The width of the slit is 1 μm. The slit is illuminated by monochromatic plane waves. If another slit of same width is made near it, Young’s fringes can be observed on a screen placed at a distance 50 cm from the slits. If the observed fringe width is 1 cm, what is slit separation distance?
(i.e. distance between the centres of each slit.)

• 100 μm

• 25 μm

• 50 μm

• 75 μm

It takes 4.6 eV to remove one of the least tightly bound electrons from a metal surface. When monochromatic photons strike the metal surface, electrons having kinetic
energy from zero to 2.2 eV are ejected. What is the energy of the incident photons ?

• 2.4 eV

• 2.2 eV

• 6.8 eV

• 4.6 eV

If the work functions of three photosensitive materials are 1 eV, 2 eV and 3 eV respectively, then the ratio of the respective frequencies of light that produce photoelectrons of maximum kinetic energy of 1 eV from each of them is

• 1 : 2 : 3

• 2 : 3 : 4

• 1 : 1 : 1

• 3 : 2 : 1