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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 × 10⁵ m s⁻¹. The speed with which electrons enters the p side will be x / 3 × 10⁵ m s⁻¹. The value of x is ____.
Give mass of electron = 9 × 10⁻³¹ kg, charge on electron = 1.6 × 10⁻¹⁹ C
- 12
- 13
- 14
- 15
Correct answer: 14
Solution
The speed of the electron decreases as it crosses the potential barrier due to energy conservation, where the kinetic energy lost equals the potential energy gained. By calculating the initial kinetic energy and equating it to the potential energy change, we find that the speed on the p-side is reduced to 4.67 × 10⁵ m/s, leading to x being 14.
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