NEET TEST SERIES 129 PHYSICS

3. The slits in Young’s double slit experiment are illuminated by light of wavelength 6000 A°. If the path difference at the central bright fright fringe is zero, what is the path difference for light from the slits at the fourth bright fringes?

(a) 2.4×10⁻⁶m
(b) 1.2×10⁻⁶m

(c) 10⁻⁶m    
(d) 0.5×10⁻⁶m

4. A narrow slit of width 2 mm is illuminated by monochromatic light of wavelength 500nm. The distance between the first minima on either side on a screen at a distance of 1 m is

(a) 5 mm
(b) 1 mm
(c) 0.5 mm
(d) 10 mm

5. The surface of a metal illuminated with the light of 400nm. The kinetic energy of the ejected photoelectrons was found to be 1.68eV. The work function of the metal is: (hc=1240eV.nm)

(a) 1.41eV   
(b) 1.51eV
(c) 1.68eV
(d) 3.09eV

6. In Young’s double slit experiment, the fringe width with light of wavelength 6000 A° is 3 mm. The fringe width, when the wavelength of light is changed to 4000 A° is

(a) 3 mm              
(b) 1 mm
(c) 2 mm
(d) 4 mm

7. When a charged conductor placed in an electrostatic field , the electric field within the plate

(a) is zero
(b) depends upon
(c) depends upon
(d) depends upon the number density of electrons

8. Find out flux  through the given Gaussian surface

9. Electric field at a point varies as

(a) for a point charge
(b) for an electric dipole
(c) inside a uniformly charged sphere
(d) outside a uniformly charged sphere

10. A uniform field  is parallel to axis of a hollow hemisphere of radius  as shown in the figure. Electric flux through the hemisperical surface is

(a) 4πR² E           
(b) πR² E
(c) 2πR² E           
(d) 4/3 π R² E

11. A gaussian surface S encloses two charges q₁ and q₂ as shown in the figure. The electric field at P is

12. In Young’s double slit experiment with a mono – chromatic light of wavelength 4000A°, the fringe width is found to be 0.4 mm. When the slits are now illuminated with a light of wavelength 5000A° the fringe width will be

(a) 0.32mm         
(b) 0.5mm
(c) 0.6mm  
(d) 0.8mm

13. If m is the mass of an electron and c the speed of light, the ratio of the wavelength of a photon of energy E to that of the electron of the same energy is

14. If alpha particle, proton and electron move with the same momentum, them their respective de Broglie wavelengths λα, λp, λe are related as

a) λα=λp=λe
b) λα<λp<λe
c) λα>λp>λe
d) λp>λe>λα

15. Assertion: Sound waves cannot be polarised.
      Reason: Sound waves are longitudinal in nature.

a) If both assertion and reason are true but reason is not the correct explanation of assertion.
b) If assertion is true but reason is false.
c) If both assertion and reason are true and reason is the correct explanation of assertion.
d) If both assertion and reason are false.

16. What is the only incorrect relation for photon?

a) Its rest mass is zero
b) Its energy is E = hv
c) Its momentum is P =hv/c
d) It does not exert pressure

17. The binding energy of the nucleus of ₂He⁴ is ( m_p=1.0073 u and m_n=1.0086 u )

a) 28.4 MeV 
b) 7.1 MeV
c) 14.2 MeV
d) 4.002 MeV

18. The number of neutrons released during the fission reaction is


a) 1
b) 3
c) 2
d) 4

19. The most abundant element in the universe is

a) Hydrogen
b) Helium
c) Oxygen
d) Carbon