A potential barrier of 0 . 4 V exists across a p-n junction. An electron enters the junction from the n -side with a speed of 6 . 0 × 10 5 m s - 1 . The speed with which electron enters the p side will be x 3 × 10 5 m s - 1 , then the value of x is _____.: (Given mass of electron = 9 × 10 - 31 kg , charge on electron = 1 . 6 × 10 - 19 C .)

Step-by-step solution

Applying conservation of energy - e V n + 1 2 m v i 2 = - e V p + 1 2 m v f 2 We know, V n - V p = potential barrier = 0 . 4   V Then, we have, - e V n - V p + 1 2 m v i 2 = 1 2 m v f 2 ⇒ - 1 . 6 × 10 - 19 × 0 . 4 + 1 2 × 9 × 10 - 31 × 36 × 10 10 = 1 2 × 9 × 10 - 31   v f 2 ⇒ - 0 . 64 × 10 - 19 + 1 . 62 × 10 - 19 = 1 2 × 9 × 10 - 31 v f 2 ⇒ 0 . 98 × 10 - 19 = 4 . 5 × 10 - 31 v f 2 ⇒ v f 2 = 0 . 98 × 10 12 4