Light — Science STD 8 — Question

Explain how can you describe vocal cords?

How many reflected rays can there be for a given single incident ray falling on a plane mirror?

Explain in brief why our head does not get crushes with atmospheric pressure.

Two persons are applying forces on two opposite sides of a moving cart. The cart still moves with the same speed in the same direction. What do you infer about the magnitudes and direction of the forces applied ?

The water which we get from sources such as taps, hand pumps, well and ponds is good conductor of electricity. Why?

How does eye adjust itself to deal with light of varying intensity?

Give one practical application of magnetic force.

Give reason why: Graphite is used for making electrode in a cell.

Explain why the surface of mortar and pestle (silbatta) used for grinding is etched again after prolonged use?

Pahell says that the reproductive life of a woman lasts from menarche to menopause. Is she right ?