Electric Charges and Fields — Physics STD 12 Science — Question

Name electromagnetic waves which are: (a) Helpful in relaxing the muscles. (b) Absorbed by the ozone layer in the atmosphere.

What is the difference between a conductor and a non-conductor?

If someone presses a pointed needle against your skin, you are hurt. But if someone presses a rod against your skin with the same force, you easily tolerate. Explain?

How is the radius of a nucleus related to its mass number?###Write the relation between radius R and mass number A of a nucleus.

Write the names of any two compound (organic) semiconductors.###Write the names of any two organic compound semiconductors.

When a current is established in a wire, the free electrons drift in the direction opposite to the current. Does the number of free electrons in the wire continuously decrease?

A convex lens is placed in contact with a plane mirror. A point object at a distance of 20 cm on the axis of this combination has its image coinciding with itself. What is the focal length of the lens?

One of your friends argues that he has read in the previous chapters that there can be no electric field inside a conductor. And hence there can be no current through it. What is the fallacy of this argument?

Which mirror does the driver use to see the traffic behind in motor vehicles and why?