A beam of light of intensity I is normally incident on a plate of area A . If plate absorbs fraction η of incident light and reflects rest of it back, then the force exerted by the incident light on the plate is given by [ c =speed of light]

Question

A beam of light of intensity I is normally incident on a plate of area A . If plate absorbs fraction η of incident light and reflects rest of it back, then the force exerted by the incident light on the plate is given by [ c =speed of light] (A) (IA/c)(1 - η) (B) (IA/c)(η + 1) (C) (IA/c)(2 η - 1) (D) (IA/c)(2 - η)

Tardigrade Admin · Accepted Answer

Force exerted by the fraction of ,ight that is absorbed is given as,

F_{1} = \frac{η I A}{c}

.
Force exerted by the fraction of light that is totally reflected is given as,

F_{2} = \frac{( 1 - η ) \times 2 I A}{c}

.
Hence, total force will be given as,

F = F_{1} + F_{2} = \frac{( 2 - η ) I A}{c}

.

Q. A beam of light of intensity $I$ is normally incident on a plate of area $A$ . If plate absorbs fraction $η$ of incident light and reflects rest of it back, then the force exerted by the incident light on the plate is given by [ $c$ =speed of light]

$\frac{I A}{c} (1 - η)$

$\frac{I A}{c} (η + 1)$

$\frac{I A}{c} (2 η - 1)$

$\frac{I A}{c} (2 - η)$

Q. A beam of light of intensity I is normally incident on a plate of area A . If plate absorbs fraction η of incident light and reflects rest of it back, then the force exerted by the incident light on the plate is given by [ c =speed of light]

cIA​(1−η)

cIA​(η+1)

cIA​(2η−1)

cIA​(2−η)

Force exerted by the fraction of ,ight that is absorbed is given as, F1​=cηIA​ . Force exerted by the fraction of light that is totally reflected is given as, F2​=c(1−η)×2IA​ . Hence, total force will be given as, F=F1​+F2​=c(2−η)IA​ .

Q. A beam of light of intensity $I$ is normally incident on a plate of area $A$ . If plate absorbs fraction $η$ of incident light and reflects rest of it back, then the force exerted by the incident light on the plate is given by [ $c$ =speed of light]

$\frac{I A}{c} (1 - η)$

$\frac{I A}{c} (η + 1)$

$\frac{I A}{c} (2 η - 1)$

$\frac{I A}{c} (2 - η)$