CONCEPTUAL PROBLEMS

1. Use graphical method to locate image of an erect object placed before a concave mirror between its pole and the focus. Hence write down the nature of image so formed.

OR Trace the position of an image formed by a concave mirror when real object is placed at a distance less than its focal length.

2. A concave mirror is often used as an aid for applying cosmetics to the face, why?
3. Convex mirrors are used as rear-view mirrors in cars, why?
4. Does focal length change when the curve mirror is dipped in liquid? Why?

OR, A spherical mirror be immersed in water. Will its focal length change?

5. Spherical mirror may behave as a plane mirror as a special case. Explain.
6. A spherical mirror is cut in half horizontally. Will an image be formed by the bottom half of the mirror? How?
7. Distinguish between real and virtual images.
8. Can a convex mirror ever form real image? Justify your answer.
9. The bottom of the side mirrors of your motorbike notes “objects in mirror closer than they appear”. Is it true? Why?

THEORY BASED PROBLEMS

10. Derive mirror formula in the case of concave mirror. Also discuss the nature of images.

OR, Point out the difference between real image and virtual image. Obtain a relation connecting the object distance, image distance and focal length of concave mirror.

11. How will you make difference between real and virtual images? Obtain an expression for the relation between object distance, image distance and the focal length in the case of convex mirror.
12. What do you mean by principal focus of a convex mirror? Prove mirror formula for a convex mirror and also show that m = v/u for the same mirror.
13. What do you understand by the principal focus of a spherical mirror? Derive relation between object distance, image distance and the focal length if object is placed between the centre of curvature and the focus of a concave mirror.
14. What should be the minimum height of a vertical plane mirror so that a person standing in front of it can see his full image?
15. Two plane mirrors are inclined to one another at an angle of 90^o. Draw a reasonable accurate ray diagram and find the number of images produced by this system.

1. At what position an object be placed in front of a concave mirror of radius of curvature 0.4 m so that an erect image of magnification 3 be produced? Ans: 13.3 cm
2. A pole 4 m long is laid along the principal axis of a convex mirror of focal length 1 m. The end of the pole nearer the mirror is 2m from it. Find the length of image of the pole. Ans: 0.190 m
3. A mirror forms an erect image 30 cm from the object and twice its height. What is its radius of curvature? Ans: 0.4 m
4. An erect image, three times the size of the object is obtained with a concave mirror of radius of curvature 36 cm. What is the position of the object? Ans: 12 cm
5. An object 10 cm high is placed infront of a convex mirror of focal length 20 cm and the object is 30 cm from the mirror. Find the height of the image. Ans: 0.04 m
6. Calculate the focal length of a concave mirror when an object placed at a distance of 40 cm makes image equal to the size of the object. Ans: 20 cm
7. A metre scale is placed along the axis of a convex mirror of focal length 25 cm, its nearer end being at a distance of 50 cm. Calculate the size of the image formed. Ans: 4.76 cm
8. A convex mirror with a radius of curvature 30 cm forms a real image 20 cm from its pole. Explain how it is possible and find whether the image is erect or inverted. Ans: u = – 8.57 cm, It is possible when object is virtual.