NEET PYQs for Dual Nature of Radiation and Matter with Solutions: Practice NEET Previous Year Questions

1.

The momentum of a photon of energy 1 MeV in kg m/s, will be :

• 0.33 x 10⁶
• 8 x 10^-24 
• 5 x 10^-23
• 5 x 10^-22 

2.

When two monochromatic light of frequency ν and \(\frac{ν}{2}\) are incident on a photoelectric metal, their stopping potential becomes \(\frac{V_s}{2}\) and V_s respectively. The threshold frequency for this metal is:

• 2 v
• 3 v
• \(\frac{2}{3v}\)

• \(\frac{3}{2v}\)

3.

An electron and an alpha particle are accelerated by the same potential difference. Let λ_e and λ_α denote the de-Broglie wavelengths of the electron and the alpha particle, respectively, then:

• \(\lambda_e > \lambda_a\)
• \(\lambda_e = 4\lambda_a\)
• \(\lambda_e = \lambda_a\)
• \(\lambda_e < \lambda_a\)

4.

A photo-cell is illuminated by a source of light,which is placed at a distance d from the cell.If the distance become d/2, then number of electrons emited per second will be

• Remain same
• Four times
• Two times
• One-fourth

5.

The work functions of Caesium (Cs), Potassium (K) and Sodium (Na) are 2.14eV, 2.30 eV and 2.75eV respectively. If incident electromagnetic radiation has an incident energy of 2.20eV, which of these photosensitive surfaces may emit photoelectrons?

• Na only

• Cs only

• Both Na and K

• K only

6.

An electromagnetic wave of wavelength ‘λ’ is incident on a photosensitive surface of negligible work function. If ‘m’ mass is of photoelectron emitted from the surface that has de-Broglie wavelength λ_d, then

• \(\lambda=(\frac{2h}{mc})\lambda d^2\)

• \(\lambda=(\frac{2m}{hc})\lambda d^2\)

• \(\lambda_d=(\frac{2mc}{h})\lambda^2\)

• \(\lambda=(\frac{2mc}{h})\lambda d^2\)

7.

A photosensitive metallic surface has work function, hv₀. If photons of energy 2hv₀ fall on this surface, the electrons come out with a maximum velocity of 4x10⁶ m/s. When the photon energy is increased to 5hv₀, then maximum velocity of photoelectrons will be:

• 16x10⁶ m/s

• 8x10⁷ m/s

• 4x10⁵ m/s

• 8x10⁶ m/s

8.

When photons of energy hv fall on an aluminum plate (of work function E₀), photoelectrons of maximum kinetic energy K are ejected. If the frequency of the radiation is doubled, the maximum kinetic energy of the ejected photoelectrons will be :

• K + E₀
• 2K
• K
• k + hv

9.

A photoelectric cell is illuminated by a point source of light 1 m away. When the source is shifted to 2 m then-

• each emitted electron carries one quarter of the initial energy
• number of electrons emitted is half the initial number
• each emitted electron carries half the initial energy
• number of electrons emitted is a quarter of the initial number

10.

If λm denotes the wavelength at which the radioactive emission from a black body at a temperature T K is maximum, then

• λ_m is independent of T

• λ_m ∝ T

• λ_m ∝ T–1

• λ_m ∝ T–4

11.

The work functions for metals A,B and C are respectively 1.92 eV, 2.0 eV and 5 eV. According to Einstein's equation, the metals which will emit photoelectrons for a radiation of wavelength 4100 Å is/are:

• none

• A only

• A and B only

• all the three metals

12.

A photon and an electron (mass \(m\)) have the same energy \(E\). The ratio \( \frac{\lambda_{\text{photon}}}{\lambda_{\text{electron}}} \) of their de Broglie wavelengths is: (\(c\) is the speed of light)

• \( c \sqrt{2mE} \)
  
• \( \frac{c \sqrt{2m}}{E} \)
  
• \( c \sqrt{\frac{E}{2m}} \)
  
• \( \sqrt{\frac{E}{2m}} \)
  

13.

According to Einstein's photoelectric equation, the graph between the kinetic energy of photoelectrons ejected and the frequency of incident radiation is

14.

When the energy of the incident radiation is increased by 20%, the kinetic energy of the photoelectrons emitted from a metal surface increased from 0.5 eV to 0.8 eV. The work function of the metal is

• 1.0 eV
• 1.3 eV
• 1.5 eV
• 0.65 eV

15.

When ultraviolet rays incident on metal plate then photoelectric effect does not occur, it occurs by incidence of 

• Infrared rays
• X-rays
• Radio wave
• Light wave