Mechanical energy is equal to

1. the sum of total energy and potential energy
2. the sum of potential energy and kinetic energy
3. the energy acquired by machines
4. All of the above

A light moves from denser to rarer medium, which of the following is correct?

1. Energy increases
2. Frequency increases
3. Velocity increases
4. None of the above

A ray of light travels from a medium of refractive index n₁ to a medium of refractive index n₂. If angle of incidence is i and angle of refraction is r, then $\dfrac{\text{sin i}}{\text{sin r}}$ is equal to

1. n₁

2. n₂

3. $\dfrac{\text{n}$2}{\text{n}1}

4. $\dfrac{\text{n}$1}{\text{n}2}

Fuse is an alloy of

1. lead and copper
2. copper and tin
3. lead and tin
4. None of the above