Physics Past Questions and Answers

A piece of radioactive material contains 10<sup style='font-size: smaller;'>20</sup> atoms. <br/>If the half life of the material is 20 seconds, the number of disintegration in the first second is

Thermionic emission is the process whereby

Which of the following can conduct electricity owing to the presence of free mobile electrons?

When a pentavalent impurity is added to a pure semiconductor, it becomes

The value of x, y and z respectively in the expression M<sup style='font-size: smaller;'>x</sup>L<sup style='font-size: smaller;'>y</sup>T<sup style='font-size: smaller;'>z</sup> for the universal gravitational constant G are