1900's Physics and Wave

Q. Colours in thin films are because of:

1. Polarisation
2. Interference
3. Reflection
4. Diffraction

Q. Calculate the frequency of a wave with wavelength $4\times {10}^7$ nm .

1. $7.5\times {10}^9{\text{s}}^{-1}$
2. $2.5\times {10}^9{\text{s}}^{-1}$
3. $7.5\times {10}^6{\text{s}}^{-1}$
4. $2.5\times {10}^6{\text{s}}^{-1}$

Q. Which of the following does not travel in vacuum?

1. Radio waves
2. Micro waves
3. Sound waves
4. X-rays

Q. Wavelengths of different radiations are given below:
$\lambda \left(A\right)=300\text{nm}\lambda \left(B\right)=300\mu \text{m}$
$\lambda \left(C\right)=30\text{nm}\lambda \left(D\right)=30\stackrel{\circ }{A}$
Arrange these radiations in the increasing order of their energies:

1. $A<B<C<D$
2. $C<B<D<A$
3. $B<A<C<D$
4. $C<D<A<B$

Q. Find the ratio of energies of violet light $({\lambda }_1=4.10\times {10}^{-5}\text{cm})$ to that of red light $({\lambda }_2=6.56\times {10}^{-5}\text{cm})$.

1. $1:1.6$
2. $1:2.6$
3. $2.6:1$
4. $1.6:1$

Q. On a rainy day, small oil films on water show brilliant colours. This is due to:

1. Dispersion
2. Interference
3. Diffraction
4. Polarisation

Q. The incorrect statement about the angle of incidence for a wave is:

1. It can be measured between the incident ray and the normal
2. It is equal to the angle of refraction
3. It is equal to the angle of reflection
4. A normal is the line perpendicular to the surface at the point of incidence

Q. Interference of light is an evidence that:

1. Light is a transverse wave
2. The speed of light is very large
3. Light has wave phenomenon
4. Light is an electromagnetic wave

Q. Which of the following statements is incorrect regarding wave theory:

1. Electromagnetic radiation travels with a velocity of $3\times {10}^8$ m/s
2. Electromagnetic waves do not require any medium for propagation
3. The distance between successive peaks and troughs is called wavelength
4. These waves consist of electric and magnetic fields perpendicular to each other and are perpendicular to the direction of propagation of the radiation

Q. A hypothetical electromagnetic wave is shown below. Find out the frequency of the radiation.

1. $6.49\times {10}^{19}{\text{s}}^{-1}$
2. $3.47\times {10}^{19}{\text{s}}^{-1}$
3. $2.47\times {10}^{19}{\text{s}}^{-1}$
4. $5.52\times {10}^{19}{\text{s}}^{-1}$