$A$ positron has nearly the same weight as that of:

Cathode rays are made up of

The increasing order for the values of $e/m$ $(\text{charge/mass})$ is :

Provide general information about the fundamental particles of an atom.

In Millikan's experiment,static electric charge on the oil drops has been obtained by shining $X$-rays. If the static electric charge on the oil drop is $-1.282 \times 10^{-18} \ C,$ calculate the number of electrons present on it.

What are cathode rays? Write down their characteristics.