If a concave mirror has a radius of curvature of 20 cm, what is its focal length

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Question: If a concave mirror has a radius of curvature of 20 cm, what is its focal length?

Options:

Correct Answer: 10 cm

Solution:

The focal length (f) of a concave mirror is half the radius of curvature (R). Therefore, f = R/2 = 20 cm / 2 = 10 cm.

If a concave mirror has a radius of curvature of 20 cm, what is its focal length?

If a concave mirror has a radius of curvature of 20 cm, what is its focal length?

Step 1: Understand that a concave mirror has a property where its focal length is related to its radius of curvature.
Step 2: Remember the formula that states the focal length (f) is half of the radius of curvature (R).
Step 3: Identify the radius of curvature given in the question, which is 20 cm.
Step 4: Use the formula f = R/2 to calculate the focal length.
Step 5: Substitute the value of R into the formula: f = 20 cm / 2.
Step 6: Perform the division: 20 cm divided by 2 equals 10 cm.
Step 7: Conclude that the focal length of the concave mirror is 10 cm.

Focal Length of Mirrors – The focal length of a concave mirror is calculated as half of its radius of curvature.