Question

Explain why $\alpha$ and $\beta -$particles are deflected in an electric or a magnetic field but $\gamma -$rays are not deflected in such a field.

Answer 1

1. A moving charged particle experiences force in an electric field as well as in a magnetic field.

suppose a charge particle has charge $q$ and moving with velocity $\overrightarrow{V}$ in an electric field is $\overrightarrow{E}$ and the magnetic field is $\overrightarrow{B}$

Then, the Force experience by charge $q$ is

In an electric field Electrostatic Force $\overrightarrow{F_e}=q\overrightarrow{E}$

And in a magnetic field Magnetic Force $\overrightarrow{F_B}=q(\overrightarrow{V}\times \overrightarrow{B})$

2. Alpha and beta particles are charged particles. Alpha is a Positively charged particle and beta is a negatively charged particle.

3. These particles are deflected in an electric or a magnetic field because alpha and beta particles experience some force in an electric or a magnetic field.

4. Gamma particles are neutral particles, so gamma rays do not experience any force on it either electric or magnetic field.

5. Therefore gamma rays are not deflected by either an electric or a magnetic field.