Class 12 Electrons Exercise 22 Solutions | The Heart of Physics KEC Publication and Distribution Pvt. Ltd.

An electric or magnetic field doesn't need to be absent when an electron passes through a space without deviation. Any of the following conditions may happen:

• Cross fields. When electric and magnetic fields are aligned perpendicularly, they form cross fields. In such a situation, an electron passes undeflected.
• No electric field but magnetic field. When an electron passes parallel or antiparallel to a magnetic field (where the electric field is absent), it suffers no deviation at all.
• No electric and magnetic fields. When an electron passes through a region with no electric and magnetic fields, it passes without deviation.

Hence, we cannot confirm the absence of electric and magnetic fields when an electron passes through a space without deviation.

No, the specific charges of an electron and proton are not the same.

Reason:

The specific charge of a particle is defined as the ratio of the magnitude of its charge to its mass, i.e., specific charge = $\rm \frac{q}{m}$.

The magnitude of the charge of both an electron and a proton are the same and are equal to $\rm | q | = e$. This means that the specific charge is inversely proportional to the mass of an electron and a proton. $\rm specific \ charge \propto \frac{1}{m}$

However, the mass of a proton is greater than that of an electron $\rm ( m_p >> m_e )$. So, the specific charge of a proton is much less than that of an electron.