51.

If the two slits in Young's double slit experiment are of unequal width, then

• the dark fringes are not perfectly dark

• the bright fringes will have unequal spacing

• the bright fringes will have unequal brightness

• the fringes do not appear

The phenomenon of polarizaton shows that light has...... nature

• dual

• particle

• transverse

• longitudinal

If n is the orbit number of the electron in a hydrogen atom, the correct statement among the following is

• electron energy varies as n²

• electron energy increases as n increases

• hydrogen emits infrared rays for the electron transition from n = ∞ to n = 1

• electron energy is zero for n = 1

In a Ruby laser, the colour of laser light is due to ........ atom

• chromium

• oxygen

• aluminium

• xenon

The radius of  ₂₉Cu⁶⁴ nucleus in Fermi is (given R₀ = 1.2 × 10^-15 m)

• 9.6

• 4.8

• 1.2

• 7.7

In a radioactive decay, an element _ZX^A emits four α-parti cles, three β-particles and eight gamma photons. The atomic number and mass number of the resulting final nucleus are

• Z − 8, A − 13

• Z − 11, A − 16

• Z − 5, A − 13

• Z − 5, A − 16

For a transistor, β = 100. The value of α is

• 0.01

• 1.01

• 0.99

• 100

The following truth table with A and B as inputs is for ....... gate

• NOR

• AND

• OR

• XOR

n photons of wavelength λ are absorbed by a black body of mass m. The momentum gained by the body is

• $\frac{\mathrm{nh}}{\mathrm{\lambda }}$

• $\frac{\mathrm{h}}{\mathrm{m\lambda }}$

• $\frac{\mathrm{mnh}}{\mathrm{\lambda }}$

• $\frac{\mathrm{nh}}{\mathrm{m\lambda }}$

A radioactive nucleus has specific binding energy E₁. It emits an α-parti cle. The resulting nucleus has specific binding energy E₂. Then

• E₂ = 0

• E₂ = E₁

• E₂ < E₁

• E₂ > E₁