# AP Class 10 Physical Science Chapter 6 Refraction of Light at Curved Surfaces

The chapter 6 of class 10 physical science refraction of light at curved surfaces, discusses the refraction of light at curved surfaces.

## Important Formulas in Chapter 6 Refraction of Light at Curved Surfaces

• The formula used when a light ray enters a medium with refractive index n2 from a medium with refractive index n1 at curved interface with a radius of curvature R is given as follows:

$\frac{n_2}{v}-\frac{n_1}{v}=\frac{n_2-n_1}{R}$

• The lens formula is given as

$\frac{1}{f}=\frac{1}{v}-\frac{1}{u}$

where u is the object distance, f is the focal length of the lens and v is the image distance

• The lens maker’s formula is given as

$\frac{1}{f}=(n-1)(\frac{1}{R_1}-\frac{1}{R_2})$

where n is the refractive index, R1 and R2 are radii of curvature and f is the focal length

In the next section, let us look at a few chapter questions to better understand the concepts discussed in the chapter.

### Chapter 6 Refraction of Light at Curved Surfaces Questions

1. How do you verify experimentally that the focal length of a convex lens is increased when it is kept in water?
2. A double convex lens has two surfaces of equal radii ‘R’ and refractive index n = 15. Find the focal length ‘f’.
3. How do you appreciate the coincidence of the experimental facts with the results obtained by a ray diagram in terms of behaviour of images formed by lenses?
4. Suppose you are inside the water in a swimming pool near an edge. A friend is standing on the edge. Do you find your friend taller or shorter than his usual height? Why?
5. Find the refractive index of the glass which is a symmetrical converging lens if its focal length is equal to the radius of curvature of its surface.

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