How can the age of a rock be determined using radioactive properties of rocks ?

The temeprature of a star can be determined using

Age of a tree can be estimated by

Determine the potential at a distance r from a point charge +q. How can the potential at a point be determined due to a number of point charges?

Age of tree can be estimated by

Age of tree can be estimated by

Age of tree can be estimated by

If soap has high alkali content it irritates skin. How can the amount of excess alkali be determined? What can be the source of excess alkali?

How resistance can be determined using the principle of Wheatstone bridge ? Derive the principle .

Use of radioactivity.

How can be said the age of a plant from its stem?