1900's Physics and Wave

Q. The equivalent weight of an element is 4. Its chloride has a vapour density 59.25. Then what is the valency of the element?

Q.

In the fundamental mode, the time taken by the wave to reach the closed end of the air-filled pipe is $0.01s.$ The fundamental frequency is

1. $25$

2. $12.5$

3. $20$

4. $15$

Q. The frequency of a wave is $6\times {10}^{15}{\text{s}}^{-1}$. Its wave number will be:

1. ${10}^5{\text{cm}}^{-1}$
2. $2\times {10}^7{\text{m}}^{-1}$
3. $2\times {10}^7{\text{cm}}^{-1}$
4. $2\times {10}^5{\text{m}}^{-1}$

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.

Can radio waves travel in a vacuum?

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

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

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

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

Q. Interference of light is an evidence that:

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

Q. The distance of the closest approach of an alpha particle fired at a nucleus with kinetic energy $K_1$ is $r_o$. The distance of the closest approach when the α – particle is fired at the same nucleus with kinetic energy $2K_1$ will be.

1. $\frac{r_o}{2}$
2. $\frac{r_o}{4}$
3. $2r_o$
4. $4r_o$

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 frequency of a wave is $6\times {10}^{15}{\text{s}}^{-1}$. Its wave number will be:

1. ${10}^5{\text{cm}}^{-1}$
2. $2\times {10}^7{\text{m}}^{-1}$
3. $2\times {10}^7{\text{cm}}^{-1}$
4. $2\times {10}^5{\text{m}}^{-1}$

Q. A certain radio station broadcasts on a frequency of $980\text{kHz (kilohertz)}$. What is the wavelength of the electromagnetic radiation broadcasted by the station?

1. 306.12 m
2. 30.61 m
3. 30.30 m
4. 310.05 m

Q. Which of the following statements is/are true?

1. The ratio of the mean speed to the rms speed is independent of temperature of gas
2. The square of the mean speed of the molecules is equal to the root mean square speed at a certain temperature
3. Mean translational kinetic energy of the gas molecules at any given temperature is independent of the molecular mass of gas
4. The square of the mean speed of the molecules is equal to the $u_{av}^2=\frac{8RT}{\pi M}$ at a certain temperature

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

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

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

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. $1.6:1$