A-Level Past Paper Question Analysis Topic: Physics - Light Refraction and Reflection
1. If the radius of a curvature of a spherical mirror is 20 cm, then its focal length is ____ cm
D. None of these
Radius of curvature = 2 x focal length
So, focal length = 1/2 x radius of curvature = 1/2 x 20 cm = 10 cm
2. Name a mirror that can give an errect and enlarged image of an image
Concave mirror forms an erect, virtual and enlarged image when the object is between focus and pole of mirror.
3. Which of the following lenses would you prefer to use while reading small letters found in a dictionary?
A. A convex lens of focal length of 50 cm
B. A concave lens of focal length of 50 cm
C. A convex lens of focal length of 5 cm
D. A concave lens of focal length of 5 cm
∙ A convex lens forms a magnified image of the object on the other side of the lens when the object is placed between the radius of curvature and the focus of the lens.
∙ The magnification of the convex lens is larger for the smaller value of the focal length. Therefore, in order to read the small letters, the convex lens of smaller focal length will be used.
Correct option: C
Drafted by Quincy (A-Level Prep)