Lakhmir Singh Physics Class 10 Solutions Page No:200
Question 42: Between which two points of concave mirror should an object be placed to obtain a magnification of:
(c) – 0.4
Solution : (a) Between focus and centre of curvature.
(b) Between pole and focus.
(c) Beyond the centre of curvature
Question 43: At what distance from a concave mirror of focal length 10 cm should an object be placed so that:
(a) its real image is formed 20 cm from the mirror ?
(b) its virtual image is formed 20 cm from the mirror ?
Question 44: If a concave mirror has a focal length of 10 cm, find the two positions where an object can be placed to give, in each case, an image twice the height of the object.
Solution : f = -10cm
Case 1: m = 2 (Image is virtual and erect)
Case 2:m = -2 (Image is real and inverted)
Question 45: A mirror forms an image which is 30 cm from an object and twice its height.
(a) Where must the mirror be situated ?
(b) What is the radius of curvature ?
(c) Is the mirror convex or concave ?
Solution : Let the image formed is virtual and erect,
v - u = 30cm
m = 2