Which of the following is not a type of equilibrium ?

1. Static
2. Dynamic
3. Neutral
4. Rolling

The correct descending order of the electro magnetic waves according to their wavelengths is

1. UV-rays, γ-rays, microwaves, infrared
2. infrared, microwaves, UV-rays, γ-rays
3. γ-rays, UV rays, Infrared rays, microwaves
4. microwaves, infrared rays, UV rays, γ-rays

The effective diameter of the circular outline of a spherical lens is known as

1. focal length
2. principal focus
3. aperture of lens
4. radius of curvature

The frequency of a source is 20 kHz. The frequency of sound wave produced by it in water and air will be

1. same as that source
2. > 20 kHz
3. < 20 kHz
4. Depend upon velocity