Question

If the power of two glasses are 1D and 2D respectively, what will be the
combined power ?
(b) 1/3 D
(c) 3D
(d) 2/3 D
(a) ID​

Answer 1

$\huge{\underline{\sf Solution:-}}$

Here

• P1=1D
• P2=2D

We know that

$\boxed{\sf P=P_1+P_2+P_3\dots}$

$\\ \tt{:}\longrightarrow P=1D+2D$

$\\ \tt{:}\longrightarrow P=(1+2)D$

$\\ \tt{:}\longrightarrow P=3D$

Hence option B is correct

Power of Lens:-

Power is the reciprocal of the focal length of a lens .

$\boxed{\sf P=\dfrac{1}{f}}$

Answer 2

Explanation:

P1=1D

P2=2D

ptotal=1D+2D =3D