Which of the following options is the correct critical angle of a diamond?

Light falls on a spherical glass surface from a point source in air. It is given that n=1.5 for the spherical glass surface and the radius of curvature is 40 cm. At which of the following positions the image is formed. if the distance of the light source from the glass surface is 100 cm?

For a ray incident from a denser to rarer medium, what is the critical angle of incidence it?

The northern lights and the aurora occurs in which of the following layers of atmosphere?

what position of the image is formed by the lens combination?

If:{ is the wavelength of the signal, then what should be the minimum size of the antenna so that it properly senses the time variation of the signal?

A point is ____ of an inch in height.

Einstein's equivalence principle says that ______.

Fast-moving currents of air that occur above the friction layer are called _____.

A 1 kg balloon at equilibrium in the air is buoyed up with a force of __________.

Henri becquerel and the curies found out that _____.