CameraIcon
CameraIcon
SearchIcon
MyQuestionIcon


Question

What is meant by power of a lens? 
You have two lenses A and B of focal lengths +10 cm and -10 cm respectively. State the nature and power of each lens. Which of the two lenses will form a virtual and magnified image of an object placed 8 cm from the lens? Draw a ray diagram to justify your answer.


Solution

Power of a lens is defined as the ability of less to converge or to diverge a beam of light. It is also defined as reciprocal of focal length in metres.
Let fA be focal length of lens A and PA be the power of lens A.
For lens A:
fA = + 10 cm = 0.1 m
Since the focal length is positive, it is a convex lens.
Now, PA=1fA=10.1=+10D.
For lens B : fB = -10 cm = - 0.1 m
Let fB be focal length of lens A and PB be the power of lens B.
Since the focal length is negative, it is a concave lens.
PB=1fB=10.1=10D. 
In case of a convex lens, image is virtual and magnified if object is placed between focus and optical centre.

Biology

Suggest Corrections
thumbs-up
 
0


similar_icon
Similar questions
View More


similar_icon
People also searched for
View More



footer-image