An electron with kinetic energy K 1 enters between parallel plates of a capacitor at an angle 'α' with the plates. It leaves the plates at angle ' β ' with kinetic energy K 2. Then the ratio of kinetic energies K 1: K 2 will be

Question

An electron with kinetic energy K 1 enters between parallel plates of a capacitor at an angle 'α' with the plates. It leaves the plates at angle ' β ' with kinetic energy K 2. Then the ratio of kinetic energies K 1: K 2 will be (A) ( sin 2 β/ cos 2 α) (B) ( cos 2 β/ cos 2 α) (C) ( cos β/ cos α) (D) ( cos β/ sin α)

Tardigrade Admin · Accepted Answer

<img class="img-fluid question-image" alt="image" src="https://cdn.tardigrade.in/img/question/physics/dff69f61dd1cef49ffe4c3d3e0e11c7e-.png" /> velocity along the plate will not change. ∴ v 1 cos α= v 2 cos β ( K 1/ K 2) ⇒ ( v 12/ v 22) =( cos 2 β/ cos 2 α)

Q. An electron with kinetic energy $K_{1}$ enters between parallel plates of a capacitor at an angle ' $α$ ' with the plates. It leaves the plates at angle ' $β$ ' with kinetic energy $K_{2}$ . Then the ratio of kinetic energies $K_{1} : K_{2}$ will be

$\frac{s i n ^{2} β}{c o s ^{2} α}$

$\frac{c o s ^{2} β}{c o s ^{2} α}$

$\frac{c o s β}{c o s α}$

$\frac{c o s β}{s i n α}$

velocity along the plate will not change.
$∴ v_{1} cos α = v_{2} cos β$
$\frac{K _{1}}{K _{2}} \Rightarrow \frac{v _{1}^{2}}{v _{2}^{2}}$
$= \frac{c o s ^{2} β}{c o s ^{2} α}$

Q. An electron with kinetic energy K1​ enters between parallel plates of a capacitor at an angle 'α' with the plates. It leaves the plates at angle ' β ' with kinetic energy K2​. Then the ratio of kinetic energies K1​:K2​ will be

cos2αsin2β​

cos2αcos2β​

cosαcosβ​

sinαcosβ​