A ray of light after refraction through a lens emerges parallel to the principle axis of the lens.the incident ray passed through
A)its optic center
B)its first focus
C)its second ficus
D)centre of curvature
Answers
b)it's first focus .......................
Answer :
OPTION B - First focus .
Reason :
➡ The ray of light has been refracted through a convex lens .
➡ The convex lens has the first focus on the left hand side of the lens and the rays of light passing through it emerges parallel to the principal axis after refraction through the lens .
Explanation :
↪ The convex lens is a converging lens .
↪ It always converges the ray of light so that it meets at a point .
↪ The actual focal point is always the second focal point .
↪ This tells us that the second focus is the point where the light rays converge which were originally parallel to the principal axis .
↪ The other focus lies behind the lens .
↪ The ray of light when passed from this point to the lens will result in a parallel beam of light which is parallel to the principal axis .
↪ The focal length is the distance between focus and optical centre .
↪ The second focal length is generally referred to as the focal length .
↪ The focus of a lens generally means the second principal focus .