Question

An electron with a speed of 1.3×106m/s collides with an atom of element X. Shortly afterward, the atom emits a 1240 nm photon. What was the electron's speed after the collision? Assume that, because the atom is so much more massive than the electron, the recoil of the atom is negligible. Hint: The energy of the photon is not the energy transferred to the atom in the collision.

Answer 1

The correct answer to the following question will be "v = 3.30×10⁵ m/s".

Step-by-step explanation:

Electron collisions may initially have led to a change or transition from, n = 1 to n = 3.

So,

Incident electrons lost (-6.5-(-2)) = -4.5 ev at energy.

From energy management,

⇒
`(1)/(2)mv-(1)/(2)m(1.3* 10^6)^2=-4.5ev((1.6* 10^(-19)J )/(ev))`

On taking "m" common, we get

⇒
`m(v^2-(1.3* 10^6)^2)=-1.44* 10^(-18)`

⇒
`9.11* 10^(-31)(v^2-(1.3* 10^6)^2)=-1.44* 10^(-18)`

⇒
`v^2-(1.3* 10^6)^2=-1.58* 10^(12)`

⇒
`v=3.30* 10^5 \ m/s`