Question

Determine $e/m$ value for proton (e = charge, m = mass):

• A. Less than $e/m$ value of electron
• B. Equal to $e/m$ value of electron
• C. Greater than $e/m$ value of electron
• D. All the above

Answer 1

Answer: (A)

Less than $e/m$ value of electron

The magnitude of charge is same for both proton and electron.

The mass of a proton is about $1850$ times the mass of an electron.

As a proton has mass very much greater than the mass of an electron, the ratio $\frac{e}{m}$ for a proton will be smaller than the corresponding value for an electron.

In fact, $\frac{e}{m}$ for an electron will be approximately $1850$ times the $\frac{e}{m}$ for a proton.

Option A is correct.