A convex lens has a focal length of 20 cm. What is the power of the lens?
Practice Questions
1 question
Q1
A convex lens has a focal length of 20 cm. What is the power of the lens?
-5 D
5 D
20 D
0.05 D
Power (P) = 1/f (in meters). f = 20 cm = 0.2 m, so P = 1/0.2 = 5 D.
Questions & Step-by-step Solutions
1 item
Q
Q: A convex lens has a focal length of 20 cm. What is the power of the lens?
Solution: Power (P) = 1/f (in meters). f = 20 cm = 0.2 m, so P = 1/0.2 = 5 D.
Steps: 4
Step 1: Understand that the power of a lens is calculated using the formula P = 1/f, where P is the power in diopters (D) and f is the focal length in meters.
Step 2: Convert the focal length from centimeters to meters. Since the focal length is given as 20 cm, we convert it to meters by dividing by 100. So, 20 cm = 20/100 = 0.2 m.
Step 3: Substitute the focal length in meters into the power formula. Now we have P = 1/0.2.
Step 4: Calculate the power. 1 divided by 0.2 equals 5. Therefore, P = 5 D.
