A convex lens is dipped in a liquid whose refractive index is equal to the refractive index of the lens. Then its focal length will:

 1 become zero. 2 become infinite. 3 become small, but non-zero. 4 remain unchanged.

Subtopic:  Lens Makers' Formula |
70%
From NCERT
AIPMT - 2003
To view explanation, please take trial in the course.
NEET 2023 - Target Batch - Aryan Raj Singh
Hints
To view explanation, please take trial in the course.
NEET 2023 - Target Batch - Aryan Raj Singh

The focal length of a glass $\left(\mu =1.5\right)$ lens in air is 20 cm. If it is dipped in water $\left(\mu =\frac{4}{3}\right)$, its focal length in water will be:

 1 80 cm 2 40 cm 3 60 cm 4 20 cm
Subtopic:  Lens Makers' Formula |
65%
From NCERT
To view explanation, please take trial in the course.
NEET 2023 - Target Batch - Aryan Raj Singh
Hints
To view explanation, please take trial in the course.
NEET 2023 - Target Batch - Aryan Raj Singh

A plane-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 μ2 and R is the radius of curvature of the curved surface of the lenses, then the focal length of the combination is:
1. R/2(μ1 + μ2)
2. R/2(μ1 - μ2)
3. R/(μ1 - μ2)
4. 2R/(μ- μ1)

Subtopic:  Lens Makers' Formula |
60%
From NCERT
NEET - 2013
To view explanation, please take trial in the course.
NEET 2023 - Target Batch - Aryan Raj Singh
Hints
To view explanation, please take trial in the course.
NEET 2023 - Target Batch - Aryan Raj Singh

A plane convex lens (µ = 1.5) has a radius of curvature $$10~\mathrm{cm}$$. It is silvered on its plane surface. The focal length of the lens after silvering is:

1. 10 cm

2. 20 cm

3. 15 cm

4. 25 cm

Subtopic:  Lens Makers' Formula |
59%
From NCERT
AIPMT - 2000
To view explanation, please take trial in the course.
NEET 2023 - Target Batch - Aryan Raj Singh
Hints
To view explanation, please take trial in the course.
NEET 2023 - Target Batch - Aryan Raj Singh

Two identical equiconvex thin lenses each of focal lengths 20 cm, made of material of refractive index 1.5 are placed coaxially in contact as shown. Now, the space between them is filled with a liquid with a refractive index of 1.5. The equivalent power of this arrangement will be:

 1 +5 D 2 zero 3 +2.5 D 4 +0.5 D
Subtopic:  Lens Makers' Formula |
55%
From NCERT
To view explanation, please take trial in the course.
NEET 2023 - Target Batch - Aryan Raj Singh
Hints