Question

1.A plastic lens has index of refraction n=1.4. If the front of the lens has radius of 1.3 m and the rear of the lens has radius of -0.9 m, what is the refractive power of the lens?1. 0.75 diopters2. 1.5 diopters3. 1.9 diopters4. -0.14 diopters

Answer 1

Given:

n = 1.4

radius of the front = 1.3 m

radius of the rear = -0.9 m

Let's find the refractive power of the lens.

To find the refractive power of the lens, apply the formula:

`(1)/(f)=(n-1)((1)/(R_1)-(1)/(R_2))`

Thus, we have:

`\begin{gathered} (1)/(f)=(1.4-1)((1)/(1.3)-(-(1)/(0.9))) \\ \\ (1)/(f)=(0.4)((1)/(1.3)+(1)/(0.9)) \\ \\ (1)/(f)=(0.4)((0.9+1.3)/(1.17)) \\ \\ (1)/(f)=(0.4)((2.2)/(1.17)) \\ \\ (1)/(f)=0.75 \end{gathered}`

Therefore, the refractive power of the lens is 0.75 diopters

• ANSWER

1. 0.75 diopters