31.

The conducting loop in the form of a circle is placed in a uniform magnetic field with its plane perpendicular to the direction of the field. An emf will be induced in the loop, if

• it is translated parallel to itself

• it is rotated about one of its diameters

• it is rotated about its own axis which is parallel to the field

• the loop is deformed from the original shape

An object is located 4 m from the first of two thin converging lenses of focal lengths 2 m and 1 m, respectively. The lenses are separated by 3 m. The final image formed by the second lens is located from the source at a distance of 

• 8.0 m

• 5.5 m

• 6.0 m

• 6.5 m

A ray of light is incident at an angle i on a glass slab of refractive index µ. The angle between reflected and refracted light is 90°. Then, the relationship between i and µ is

• $\mathrm{i} = {\tan }^{-1} \left(\frac{1}{\mathrm{\mu }}\right)$

• tan i = µ

• sin i = µ

• cos i = µ

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

When light is refracted from a surface, which of its following physical parameters does not change ?

• Velocity

• Amplitude

• Frequency

• Wavelength

The inputs to the digital circuit are as shown below. The output Y is

• $\mathrm{A}\hspace{0.17em}+ \mathrm{B} + \overline{\mathrm{C}}$

• $\left(\mathrm{A}\hspace{0.17em}+ \mathrm{B}\right) \overline{\mathrm{C}}$

• $\overline{\mathrm{A}} + \overline{\mathrm{B}} + \overline{\mathrm{C}}$

• $\overline{\mathrm{A}} + \overline{\mathrm{B}} + \mathrm{C}$

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

A thin plastic sheet of refractive index 1.6 is used to cover one of the slits of a double slit arrangement. The central point on the screen is now occupied by what would have been the 7th bright fringe before the plastic was used. If the wavelength of light is 600 nm, what is the thickness (in µm) of the plastic sheet ?

• 7

• 4

• 8

• 6

Find the right condition(s) for Fraunhoffer diffraction due to a single slit.

• Source is at infinite distance and the incident beam has converged at the slit.

• Source is near to the slit and the incident beam is parallel

• Source is at infinity and the incident beam is paralle

• Source is near to the slit and the incident beam has converged at the slit

Consider two particles of different masses. In which of the following situations the heavier of the two particles will have smaller de-Broglie wavelength ?

• Both have a free fall through the same height

• Both move with the same kinetic energy

• Both move with the same linear momentum

• Both move with the same speed