Question

A convex lens
power 5D
and a concave lens of power
- 4D is kept in contact the power of
The combination is :-
Ans
(a) 5D
(b) -5D (C) 1d (d) 9D​

Answer 1

Given :

▪ Power of convex lens = 5D

▪ Power of concave lens = -4D

▪ Both are kept in contact.

To Find :

▪ Power of the combination.

Formula :

↗ The equivalent power of thin lenses in contact is given by

$\bigstar\:\underline{\boxed{\bf{\red{P=P_1+P_2+P_3+...+P_n}}}}$

Where P1, P2, P3... are powers of individual lenses.

Calculation :

$\dashrightarrow\sf\:P=P_1+P_2\\ \\ \dashrightarrow\sf\:P=5+(-4)\\ \\ \dashrightarrow\sf\:P=5-4\\ \\ \dashrightarrow\underline{\boxed{\bf{\blue{P=1D}}}}\:\orange{\bigstar}$

Answer 2

$\large {\bf {\underline {Question}}}$

A convex lens power 5D and a concave lens of power - 4D is kept in contact the power of the combination is :-

(a) 5D (b) -5D (C) 1d (d) 9D

$\large {\bf {\underline {Answer}}}$

$\rm {\underline {Given}}$

Power of convex lens = 5D

Power of concave lens = -4D

=>The both lens are kept in contact.

$\rm {\underline {To\:Find}}$

Power of combination.

$\rm {\underline {Solution}}$

$\tt P = P_1 + P_2 \\ \tt P = 5 + (-4) \\ \tt P = 5 - 4 \\ \tt \implies \boxed {\pink {P = 1D}}$

_______________________________

$\rm {\underline {Formula\:used}}$

$\tt {\red {P = P_1 + P_2 + P_3 + ... + P_n}}$

$\rm {Here\:P_1 , P_2 , P_3 ,\: ......\:are\:the\:powers\:of\:individual\:lenses}$

Hope it helps dear...