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Physics · PYQ NEET UG 2018
हिन्दीAn electron of mass \( m \) with an initial velocity \( \vec{v} = v_0 \hat{i} \) (\( v_0 > 0 \)) enters an electric field \( \vec{E} = -E_0 \hat{i} \) (\( E_0 = \text{constant} > 0 \)) at \( t = 0 \). If \( \lambda_0 \) is its de-Broglie wavelength at time \( t \) is
Correct answer · Option 1
\( \frac{\lambda_0}{(1+\frac{eE_0 t}{m v_0})} \)
Explanation
De-Broglie wavelength is \( \lambda = \frac{h}{p} \). The velocity at time \( t \) is \( v = v_0 + \frac{eE_0 t}{m} \) since the force is in the direction of motion. Hence \( \lambda = \frac{\lambda_0}{1 + \frac{eE_0 t}{m v_0}} \).
