$A$ plane polarized light is incident on a polarizer with its pass axis making an angle $\theta$ with the $x-$axis,as shown in the figure. At four different values of $\theta$,namely $\theta = 8^o, 38^o, 188^o$ and $218^o$,the observed intensities are the same. What is the angle between the direction of polarization and the $x-$axis in degrees?

The wave property of electrons implies that they will show diffraction effects. Davisson and Germer demonstrated this by diffracting electrons from crystals. The law governing the diffraction from a crystal is obtained by requiring that electron waves reflected from the planes of atoms in a crystal interfere constructively. Which of the following phenomena establishes the transverse nature of light?

'n' polarizing sheets are arranged such that each makes an angle $45^\circ$ with the preceding sheet. An unpolarized light of intensity $I$ is incident into this arrangement. The output intensity is found to be $I/64$. The value of $n$ will be

Through which characteristic can we distinguish light waves from sound waves?

Two polaroids are oriented with their planes perpendicular to incident light and their transmission axes making an angle of $30^{\circ}$ with each other. What fraction of the incident unpolarised light is transmitted? (Express as a percentage)

Two polaroids $P_1$ and $P_2$ are placed with their axes perpendicular to each other. Unpolarised light of intensity $I_0$ is incident on $P_1$. $A$ third polaroid $P_3$ is kept in between $P_1$ and $P_2$ such that its axis makes an angle $45^{\circ}$ with that of $P_1$. The intensity of transmitted light through $P_2$ is