A student has obtained an image of a well-illuminated distant object on a screen to determine the focal length, f1 of the given spherical mirror. The teacher then gave him another mirror of focal length, f2 and asked him to obtain a focussed image of the same object on the same screen. The student found that in order to focus the same object using the second mirror, he has to move the mirror away from the screen. From this observation it may be concluded that both the spherical mirrors given to the student were (select the correct option)
A. Concave and f2 > f1
B. Concave and f1 > f2
C. Convex and f2 < f1
D. Convex and f1 > f2
Answer:A
A student has obtained an image of a well-illuminated distant object on a screen to determine the focal length, f1 of the given spherical mirror. The teacher then gave him another mirror of focal length, f2 and asked him to obtain a focussed image of the same object on the same screen. The student found that in order to focus the same object using the second mirror, he has to move the mirror away from the screen. From this observation it may be concluded that both the spherical mirrors given to the student were (select the correct option)
A. Concave and f2 > f1 B. Concave and f1 > f2 C. Convex and f2 < f1 D. Convex and f1 > f2
Explanation: Concave mirror will give the real focus and on moving the mirror away from the screen “f2” is greater than f1.