JEE Main 2022 · 26 Jun · Shift 1 · Physics Q47

← JEE Main 2022 · 26 Jun · Shift 1

PhysicsSingle correct+4 / -1Question 47 of 90

An electron with speed $v$ and a photon with speed c have the same de-Broglie wavelength. If the kinetic energy and momentum of electron are $E_e$ and $p_e$ and that of photon are $E_{ph}$ and $p_{ph}$ respectively. Which of the following is correct ?

\dfrac{E_e}{E_{ph}}=\dfrac{2c}v

\dfrac{E_e}{E_{ph}}=\dfrac v{2c}

\dfrac{p_e}{p_{ph}}=\dfrac{2c}v

\dfrac{p_e}{p_{ph}}=\dfrac v{2c}

Answer and worked solution

Official answer: B

Same wavelength means same momentum: $p_e=p_{ph}=p$ .

Energies. $E_e=\dfrac{p^2}{2m}=\dfrac{pv}2$ and $E_{ph}=pc$ , so $\dfrac{E_e}{E_{ph}}=\dfrac v{2c}$ .

(B)

Topics:de Broglie waves Photon momentum and radiation pressure

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JEE Main 2022 · 26 Jun · Shift 1, Physics question 47