Question

In Thomson experiment of finding e/m for electrons, beam of electron is replaced by that of muons (particle with same charge as of electrons but mass 208 times that of electrons). No deflection condition in this case satisfied if

• A. B is increased 208 times
• B. E is increased 208 times
• C. B is increased 14.4 times
• D. None of these

Answer 1

Answer: (C)

B is increased 14.4 times

Answer 2

In the condition of no deflection$\frac{e}{m} = \frac{E^{2}}{2VB^{2}}$. If m is increased to 208 times then B should be increased by $\sqrt{208} = 14.4\text{times.}$