Advertisements
Advertisements
Question
If each two concave lenses of focal length 30 cm are kept in contact with each other what will be the power of combination?
Advertisements
Solution
Given: f1 = f2 = – 30 cm = – 0.3 m
To find: Power of combination (P)
Formula: P = `1/"f" = 1/"f"_1 + 1/"f"_2`
Calculation: From formula,
P = `1/(- 0.3) + 1/(- 0.3)`
`= (- 10)/3 + (- 10)/3`
`= (- 20)/3` = - 6.7 D
Power of combination is – 6.7 D.
APPEARS IN
RELATED QUESTIONS
Solve the following example.
Three lenses having power 2, 2.5 and 1.7 D are kept touching in a row. What is the total power of the lens combination?
An object is placed at a distance of 10 cm from a convex lens of focal length 12 cm, find out at what distance image will be formed from the lens and what is the nature of image.
5 cm high object is placed at a distance of 10 cm from a converging lens of focal length of 20 cm. Determine the position, size and type of the image.
Two convex lenses of focal length 30 cm and 10 cm each are kept in contact with each other. Find the power of their combination.
