A potential barrier of 0.4V exists across a p-n junction. An electron enters the junction from the n-side with a speed of 6.0 * 105. The speed with which electron enters the p side will be x 3 * 1 0 5 m s − 1 the value of x is__________. (Given mass of electron = 9 * 10-31 kg, charge on electron = 1.6 * 10-19 C.)

According to Work energy theorem, we can write Kf−Ki=WElectric Force⇒12mv2−12mv02=−eV⇒v2=v02−2eVm ⇒v2= (6.0*105)2−2*1.6*10−199*10−31=324−1289*1010=1969*1010⇒V=143*105m/s

A potential barrier of 0.4V exists across a p-n junction. An electron enters the junction from the n-side with a speed of 6.0 * 10⁵. The speed with which electron enters the p side will be $\frac{x}{3} * 1 0^{5} m s^{- 1}$ the value of x is__________.

**(Given mass of electron = 9 * 10^-³¹ kg, charge on electron = 1.6 * 10^-¹⁹ C.)**

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Payal Gupta | Contributor-Level 10

6 months ago

According to Work energy theorem, we can write

$K_{f} - K_{i} = W_{E l e c t r i c F o r c e} \Rightarrow \frac{1}{2} m v^{2} - \frac{1}{2} m v_{0}^{2} = - e V \Rightarrow v^{2} = v_{0}^{2} - \frac{2 e V}{m}$

$\Rightarrow v^{2} = {(6.0 * 1 0^{5})}^{2} - \frac{2 * 1.6 * 1 0^{- 19}}{9 * 1 0^{- 31}} = \frac{324 - 128}{9} * 1 0^{10} = \frac{196}{9} * 1 0^{10} \Rightarrow V = \frac{14}{3} * 1 0^{5} m / s$