An electron and a photon have same wavelength of 10-9 m. If E is the energy of the photon and p is the momentum of the electron, then the magnitude of E / p (in SI unit) is

Question

An electron and a photon have same wavelength of 10-9 m. If E is the energy of the photon and p is the momentum of the electron, then the magnitude of E / p (in SI unit) is (A) 1.00 x 10-9 (B) 1.50 x 108 (C) 3.00 x 108 (D) 1.20 x 107

Tardigrade Admin · Accepted Answer

For a photon energy is E=hf=(hc/λ) For an momentum of electron is P=(h/λ) So, (E/p)=(hc/ λ/h / λ) =c here, λ is same for both photon and electron. ⇒ (E/P)=3×108ms-1

Q. An electron and a photon have same wavelength of $1 0^{- 9} m$ . If $E$ is the energy of the photon and $p$ is the momentum of the electron, then the magnitude of $E / p$ (in SI unit) is

$1.00$ x $1 0^{- 9}$

$1.50$ x $1 0^{8}$

$3.00$ x $1 0^{8}$

$1.20$ x $1 0^{7}$

For a photon energy is
$E = h f = \frac{h c}{λ}$
For an momentum of electron is $P = \frac{h}{λ}$
So, $\frac{E}{p} = \frac{h c / λ}{h / λ} = c$
here, $λ$ is same for both photon and electron.
$\Rightarrow \frac{E}{P} = 3 \times 1 0^{8} m s^{- 1}$

Q. An electron and a photon have same wavelength of 10−9m. If E is the energy of the photon and p is the momentum of the electron, then the magnitude of E/p (in SI unit) is

1.00 x10−9

1.50 x 108

3.00 x 108

1.20 x 107