A student focussed the image of a distant object using a device ‘X’ on a white screen ‘S’ as shown in figure. If the distance of the screen from the device is 40 cm, select the correct statement about the device.
A. The device X is a convex lens of focal length 20 cm.
B. The device X is a concave mirror of focal length 40 cm.
C. The device X is a concave mirror of radius of curvature 40 cm.
D. The device X is a convex lens of focal length 40 cm.
Answer:D
A student focussed the image of a distant object using a device ‘X’ on a white screen ‘S’ as shown in figure. If the distance of the screen from the device is 40 cm, select the correct statement about the device.
A. The device X is a convex lens of focal length 20 cm. B. The device X is a concave mirror of focal length 40 cm. C. The device X is a concave mirror of radius of curvature 40 cm. D. The device X is a convex lens of focal length 40 cm.
Explanation: Convex lens converges all the rays and the distance between lens and focus is 40 cm.