Q.43. An electron is travelling with a velocity v in free space and when it enters a medium, its vel

Q: What is the correct answer for JEE Main Physics Q43?

The correct answer is C. The de Broglie wavelength is given by $\lambda = \frac{h}{mv}$. In free space, velocity is $v_0 = v$, so $\lambda_0 = \frac{h}{mv}$. In the medium, velocity is reduced by 20%, so $v' = v - 0.20v = 0.80v$. The de Broglie wavelength in the medium is $\lambda' = \frac{h}{mv'}$. We are given $\lambda' = \alpha \lambda_0$. So, $\alpha = \frac{\lambda'}{\lambda_0}$. $\alpha = \frac{h/(mv')}{h/(mv)} = \f

Q: Q.43. An electron is travelling with a velocity v in free space and when it enters a medium, its velocity is reduced by 20%. The de Broglie wavelength of electron in the medium is , where is its de…

The correct answer is C. The de Broglie wavelength is given by $\lambda = \frac{h}{mv}$. In free space, velocity is $v_0 = v$, so $\lambda_0 = \frac{h}{mv}$. In the medium, velocity is reduced by 20%, so $v' = v - 0.20v = 0.80v$. The de Broglie wavelength in the medium is $\lambda' = \frac{h}{mv'}$. We are given $\lambda' = \alpha \lambda_0$. So, $\alpha = \frac{\lambda'}{\lambda_0}$. $\alpha = \frac{h/(mv')}{h/(mv)} = \f

Q: What are the options for this JEE Main Physics question?

A. 20 · B. 0 · C. 25 · D. 75

Question

Q.43. An electron is travelling with a velocity v in free space and when it enters a medium, its velocity is reduced by 20%. The de Broglie wavelength of electron in the medium is , where  is its de Broglie wavelength in free space. The value of  is

FirstInTest · Accepted Answer

The de Broglie wavelength is given by $\lambda = \frac{h}{mv}$.
In free space, velocity is $v_0 = v$, so $\lambda_0 = \frac{h}{mv}$.
In the medium, velocity is reduced by 20%, so $v' = v - 0.20v = 0.80v$.
The de Broglie wavelength in the medium is $\lambda' = \frac{h}{mv'}$.
We are given $\lambda' = \alpha \lambda_0$. So, $\alpha = \frac{\lambda'}{\lambda_0}$.
$\alpha = \frac{h/(mv')}{h/(mv)} = \frac{v}{v'} = \frac{v}{0.80v} = \frac{1}{0.80} = \frac{100}{80} = \frac{10}{8} = \frac{5}{4} = 1.25$.
Thus, $\alpha = 1.25$.

Answer

20

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0

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25

Answer

75

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