Lenz's law is based on the law of conservation of:

1. force
2. charge
3. mass
4. energy

Heat capacity of a body is:

1. the energy needed to melt the body without the change in its temperature.
2. the energy needed to raise the temperature of the body by 1°C
3. the increase in the volume of the body when its temperature increases by 1°C
4. the total amount of internal energy that is constant.

When a ray of light enters from a denser medium to a rarer medium then:

1. the light ray bends towards the normal
2. the speed of light increases
3. the angle of incidence is greater than the angle of refraction
4. its wavelength decreases.

An endoscope uses optical fiber to transmit high resolution images of internal organs without loss of information. The phenomenon of light that governs the functioning of the optical fiber is:

1. refraction
2. reflection
3. scattering
4. total internal reflection