Practicing Success

Target Exam

CUET

Subject

Physics

Chapter

Dual Nature of Radiation and Matter

Question:

A particle moves in a closed orbit around the origin, due to a force which is directed towards the origin. The de Broglie wavelength of the particle varies cyclically between two values $λ_1$ and $λ_2$ with $λ_1>λ_2$. Which of the following statements is true?

Options:

The particle could be moving in a circular orbit with origin as centre

The particle could be moving in an elliptic orbit with origin as its focus

When the de Broglie wavelength is $λ_1$, the velocity of particle is more than when its value is $λ_2$

Both (1) and (3)

Correct Answer:

The particle could be moving in an elliptic orbit with origin as its focus

Explanation:

The de Broglie wavelength of the particle can be varying cyclically between two values $λ_1$ and $λ_2$, if particle is moving in an elliptical orbit with origin as its one focus.

Let $v_1 , v_2$ be the speed of particle at A and B respectively and origin is at focus O. If $λ_1,λ_2$ are the de Broglie wavelengths associated with particle while moving at A and B respectively.

Then

$λ_1=\frac{h}{mv_1}$ and $λ_2=\frac{h}{mv_2}$

$∴\frac{λ_1}{λ_2}=\frac{v_2}{v_1}$

Since $λ_1>λ_2$

$∴v_2>v_1$

Thus, option (2) is true.