Question

What fraction of its energy does an electron radiate per sec?

• A. $2.8\times {10}^{-8}{s}^{-1}$
• B. $3.2\times {10}^{-8}{s}^{-1}$
• C. $6\times 10s^{-1}$
• D. none of these

Answer 1

Answer: (A)

$2.8\times {10}^{-8}{s}^{-1}$

We know $r=\frac{mv}{qB}$

qB = $\frac{\sqrt{2KEm}}{r}$

F = qvB = $\frac{\sqrt{2KEm}}{r}\times$ v

a = $\frac{F}{m}$ = $\frac{2KE}{mr}$

$\frac{\frac{dE}{dt}}{6Mev}=\frac{\frac{q^2{a}^2}{6\pi {ϵ}_o{c}^3}}{6Mev}$

Mass of electron is $9.1\times {10}^{-31}$ kg and charge is $1.6\times {10}^{-19}$ C

solving the above equation with above values will give us $2.8\times {10}^{-11}{s}^{-1}$