$A$ body is sliding down a rough inclined plane. The coefficient of friction between the body and the plane is $0.5$. The ratio of the net force required for the body to slide down and the normal reaction on the body is $1:2$. Then the angle of the inclined plane is: (in $^{\circ}$)

What is preserved in a museum?

In the figure,suppose the transmission axes of the left and right polarizing disks are perpendicular to each other. Also,let the center disk be rotated on the common axis with an angular speed $\omega$. If unpolarized light is incident on the left disk with an intensity $I_{max}$,the intensity of the beam emerging from the right disk is given by:

The covalent alkaline earth metal halide $(X = Cl, Br, I)$ is

The diagram of a logic circuit is given below. The output $F$ of the circuit is represented by

The angle between the tangents drawn to the parabola $y^2=4x$ from the point $(1,4)$ is