Two identical thin plano-convex glass lenses (refractive index = 1.5) each having radius of curvature of 20 cm are placed with their convex surfaces in contact at the centre. The intervening space is filled with oil of refractive index 1.7. The focal length of the combination is:
1. -20 cm
2. -25 cm
3. -50 cm
4. 50 cm

Subtopic:  Lens Makers' Formula |
To view explanation, please take trial in the course below.
NEET 2023 - Target Batch - Aryan Raj Singh
To view explanation, please take trial in the course below.
NEET 2023 - Target Batch - Aryan Raj Singh
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A plano-convex lens fits exactly into a plano concave lens. Their plane surfaces are parallel to each other. If lenses are made of different materials of refractive indices μ1 and μand R is the radius of curvature of the curved surface of the lenses, then the focal length of the combination is:
1. $\frac{\mathrm{R}}{2\left({\mathrm{\mu }}_{1}-{\mathrm{\mu }}_{2}\right)}$
2. $\frac{\mathrm{R}}{\left({\mathrm{\mu }}_{1}-{\mathrm{\mu }}_{2}\right)}$
3. $\frac{2\mathrm{R}}{\left({\mathrm{\mu }}_{2}-{\mathrm{\mu }}_{1}\right)}$
4. $\frac{\mathrm{R}}{2\left({\mathrm{\mu }}_{1}+{\mathrm{\mu }}_{2}\right)}$
Subtopic:  Lens Makers' Formula |
To view explanation, please take trial in the course below.
NEET 2023 - Target Batch - Aryan Raj Singh
To view explanation, please take trial in the course below.
NEET 2023 - Target Batch - Aryan Raj Singh
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When a biconvex lens of glass having a refractive index of 1.47 is dipped in a liquid, it acts as a plane sheet of glass. The liquid must have a refractive index:

1. equal to that of glass.

2. less than one.

3. greater than that of glass.

4. less than that of glass.

Subtopic:  Lens Makers' Formula |
To view explanation, please take trial in the course below.
NEET 2023 - Target Batch - Aryan Raj Singh
To view explanation, please take trial in the course below.
NEET 2023 - Target Batch - Aryan Raj Singh
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A biconvex lens $\left(\mathrm{\mu }=1.5\right)$ has a radius of curvature of magnitude 20 cm. Which one of the following options, best describes, the image formed by an object of height 2 cm placed 30 cm from the lens?

1. virtual, upright, height = 0.5 cm
2. real, inverted, height = 4 cm
3. real, inverted, height = 1 cm
4. virtual, upright, height = 1 cm

Subtopic:  Lenses | Lens Makers' Formula | Refraction at Curved Surface |
To view explanation, please take trial in the course below.
NEET 2023 - Target Batch - Aryan Raj Singh
To view explanation, please take trial in the course below.
NEET 2023 - Target Batch - Aryan Raj Singh