Question 308: Ray Optics

Question

The graph between $$\frac{1}{u}$$ and $$\frac{1}{v}$$ for a thin convex lens in order to determine its focal length is plotted as shown in the figure. The refractive index of lens is $$1.5$$ and its both the surfaces have same radius of curvature $$R$$. The value of $$R$$ will be ____________ $$\mathrm{cm} .$$ (where $$u=$$ object distance, $$v=$$ image distance)

Accepted Answer

$$f = 10$$ cm
$${1 \over f} = (\mu  - 1)\left( {{1 \over R} - {1 \over { - R}}} ight)$$
$${1 \over {10}} = {{1.5 - 1} \over 1} 	imes {2 \over R}$$
$$ {1 \over {10}} = {1 \over R}$$
$$R = 10$$ cm

Ray Optics

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