Magnetism and Matter — Physics STD 12 Science — Question

Which of the following is correct for resistance of a material ?

In an experiment of photoelectric effect the number of photoelectrons has to be increased without changing their frequency. The suitable step to be taken about the incident radiation for this is:

Consider the motion of the tip of the minute hand of a clock. In one hour:

1. The displacement is zero.
2. The distance covered is zero.
3. The average speed is zero.
4. The average velocity is zero.

If the equivalent resistance is to be increased, then the number of resistances should be connected in:

A wall clock uses a vertical spring-mass system to measure the time. Each time the mass reaches an extreme position, the clock advances by a second. The clock gives correct time at the equator. If the clock is taken to the poles it will:

1. Run slow.
2. Run fast.
3. Stop working.
4. Give correct time.

When a lens is dipped into the water its focal length :