Radius of curvature of two lenses are π 1 and π 2 whose refractive index π1 and π2. Ratio of focal length isΒ
1
\(\frac{\left(\mu_{1}-1\right)}{\left(\mu_{2}-1\right)} \frac{R_{2}}{R_{1}}\)
2
\(\frac{\mu_{1} R_{2}}{\mu_{2} R_{1}}\)
3
\(\frac{\left(\mu_{2}-1\right)}{\left(\mu_{1}-1\right)} \frac{R_{1}}{R_{2}}\)
4
\(\frac{R_{2}}{R_{1}}\)