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Question
What do you understand by the focus and focal length of a spherical mirror? Show them on the separate diagrams for each of a concave mirror and a convex mirror.
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Solution
FOCUS: For concave mirror
“A point on the principal axis at which the light rays incident parallel to the principal axis meet after reflection from the mirror.
FOCAL LENGTH: “The distance between focus and pole”. FP is focal length for a concave mirror.
FOCUS: For Convex mirror
“A point on its principal axis at which the light rays incident parallel to the principal axis appear to meet after reflection from the mirror”.
FOCAL LENGTH: “The distance between P and F is F.L.”
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