Question

Wavelength associated with an electron having kinetic energy $3\times {10}^{-25}J$ is $x\times {10}^{-7}m$. What is the value of $x$?

• A. 9
• B. 4
• C. 5
• D. 6

Answer 1

The correct option is A 9

$\begin{array}{c}\lambda =\frac{h}{\sqrt{2mK.E.}}=x\times {10}^{-7}\\ \Rightarrow x=\frac{6.63\times {10}^{-34}\times {10}^7}{\sqrt{2\times 9\times {10}^{-31}\times 3\times {10}^{-25}}}\\ =\frac{6.63\times {10}^{-27}}{\sqrt{54}\times {10}^{-28}}\\ =\mathrm{9.02.}\\ Ans.\left(A\right)\end{array}$