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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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RELATED QUESTIONS
Define the following term in the context of spherical mirrors:- Pole
An image formed by a ______ mirror is always of the same size as that of the object.
A virtual image larger than the object can be produced by a ______.
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Illustrate your answer with the help of a ray diagram.
(a) When a concave mirror is used as a shaving mirror, where is the person's face in relation to the focus of mirror?
(b) State three characteristics of the image seen in part (a).
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Define the following term:
convex mirror
Does the mirror name by your form a real image for all locations? Give a reason for your answer.
Define the term Normal.
