If the focal length of a convex lens is 25 cm, what is the power of the lens? (2
Practice Questions
Q1
If the focal length of a convex lens is 25 cm, what is the power of the lens? (2023)
+2 D
+4 D
+5 D
+10 D
Questions & Step-by-Step Solutions
If the focal length of a convex lens is 25 cm, what is the power of the lens? (2023)
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 1 meter = 100 centimeters, we convert 25 cm to meters: 25 cm = 25/100 = 0.25 meters.
Step 3: Substitute the focal length in meters into the power formula: P = 1/0.25.
Step 4: Calculate the power: P = 1/0.25 = 4.
Step 5: Since the lens is convex, the power is positive, so we write it as +4 D.
Lens Power Calculation – The power of a lens is calculated using the formula P = 1/f, where f is the focal length in meters.
