Question: If a lens has a power of -2 D, what is its focal length?
Options:
-50 cm
-25 cm
25 cm
50 cm
Correct Answer: -25 cm
Solution:
Power (P) = 1/f, so f = 1/P = 1/(-2) = -0.5 m = -50 cm.
If a lens has a power of -2 D, what is its focal length?
Practice Questions
Q1
If a lens has a power of -2 D, what is its focal length?
-50 cm
-25 cm
25 cm
50 cm
Questions & Step-by-Step Solutions
If a lens has a power of -2 D, what is its focal length?
Step 1: Understand that the power of a lens (P) is related to its focal length (f) by the formula P = 1/f.
Step 2: Rearrange the formula to find the focal length: f = 1/P.
Step 3: Substitute the given power into the formula: f = 1/(-2).
Step 4: Calculate the focal length: f = -0.5 m.
Step 5: Convert the focal length from meters to centimeters: -0.5 m = -50 cm.
Lens Power and Focal Length – The relationship between the power of a lens and its focal length, where power is the inverse of the focal length (P = 1/f).
Soulshift Feedback×
On a scale of 0–10, how likely are you to recommend
The Soulshift Academy?
