List of top Questions asked in BHU PET- 2019

The polarizability of atoms in the air molecule is \( 9.7 \times 10^{-41} \, \text{cm}^2/\text{V} \). The radius of the atom of an air molecule is:
Circularly polarized light is produced if the amplitudes of the ordinary and extraordinary rays are equal and there is a phase difference of:
When a single slit is replaced by a double-slit arrangement, the intensity of the central maximum is increased by:
In the diffraction pattern due to a single slit, the width of the central maximum will be:
In a plane transmission grating, the angle of diffraction for the second-order principal maxima for wavelength \( 5000 \) Å is \( 30^\circ \). The number of lines per cm of the grating surface is:
If \( N \) is the total number of rulings on the grating, \( n \) is the order of the spectrum, and \( \lambda \) is the wavelength of light, then the resolving power of the grating is:
The minimum number of lines in a plane diffraction grating required to just resolve the sodium doublet (5890 Å and 5896 Å) in first order is:
A movable mirror of Michelson’s interferometer is moved through a distance of 0.06 mm. If 200 fringes cross the field of view, the wavelength of light is:
In interference with coherent sources, the fringe width varies as:
In Newton’s rings experiment with two different media between the glass surfaces, the nth rings have diameters as 10:7. The ratio of the refraction indices of two media are:
Broad sources are required in:
Which of the following statements is correct?
Which of the following is not correct for the first order phase transition?
If in a capillary tube the rate of flow of a liquid is measured by collecting 100 ml of liquid in 100 sec in a measuring flask. If the least count of the volume of the measuring flask be 1 ml and the least count of the stop watch used for measuring the time be 0.01 sec, then the uncertainty in the rate of flow of the liquid will be:
A clock keeps correct time. With what speed should it be moved relative to an observer so that it may seem to lose 20 sec in 100 sec?
With what velocity should an electron move so that its kinetic energy equals its rest mass energy?
Which of the following values of Poisson’s ratio can not be possible?
If two cylinders (one hollow and other solid) of same length, mass, and material are given, then, to twist the cylinders through the same angle:
In a ballistic galvanometer, \( \theta_0 \) be the throw in the absence of damping and \( \theta_1 \) be the first throw after \( \frac{T}{4} \) sec (where \( T \) is the time period of oscillations). The correct relation between \( \theta_0 \), \( \theta_1 \) & logarithmic decrement \( \lambda \) of the galvanometer will be:
If the volume of a cube of side \( L_0 \) is \( L_0^3 \) as observed by an observer at rest relative to it, the volume as observed from a reference frame moving with uniform velocity \( 0.8c \) in a direction parallel to an edge of the cube will be:
The path of a particle situated on the rim of a wheel moving along a surface (wheel is rotating) as observed by an observer standing on the earth near the wheel will be:
A particle collides elastically with another particle at rest. If the masses of the particles be \( m_1 \) and \( m_2 \) respectively, then the fraction of kinetic energy transferred to the second will be maximum when:
When a wire is stretched to double its length:
If 5th January, 1991 was Saturday, then what day of the week was it on 4th March 1992?
Read following statements carefully and answer the questions :
Out of four friends A, B, C and D : 
(A) A and B play Football and Cricket 
(B) B and C play Cricket and Hockey 
(C) A and D play Basketball and Football 
(D) C and D play Hockey and Basketball