Question

The focal length, is positive for a concave mirror, and negative for a convex mirror.

Is it ryt or wrong. I got it when I search it on internet.
Give answer with full explanation...
Best of luck.....

Answer 1

this is false actually concave mirror is negative and convex mirror is positive

Answer 2

⭐⭐⭐⭐⭐ ANSWER ⭐⭐⭐⭐⭐




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❄❄❄❄ MIRROR ❄❄❄❄

➡ A mirror is a highly polished smooth glass with a shining surface.

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❄❄❄ SPHERICAL MIRROR ❄❄❄

➡ A spherical mirror is a mirror which is made from a part of a hollow sphere.

➡ It is of two types :- CONCAVE MIRROR & CONVEX MIRROR.

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❄❄❄ DISCUSSION ❄❄❄

➡ For concave mirrors, the immage can be both REAL and VIRTUAL.

➡ For convex mirrors, the image is always virtual.

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❄❄❄ INTRODUCTION ❄❄❄

Let, u = object distance from pole of a mirror.

v = image distance from pole of a mirror.

f = focal length of that spherical mirror.

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⚡ FOR CONCAVE MIRROR :-

➡ When the image is real, then "u" is always negative, "v" is always negative, ''f" is also always negative.

➡ When the image is virtual, then "u'' is as it is negative, "v" is positive, ''f'' is negative.

THUS, IN CASE OF CONCAVE MIRROR, FOCAL LENGTH ALWAYS REMAINS NEGATIVE.

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⚡ AGAIN, FOR CONVEX MIRROR :-

➡ "u'' is always negative, "v" is positive and "f"
is also always positive.

THUS, IN CASE OF COVEX MIRROR, FOCAL LENGTH ALWAYS REMAINS POSITIVE.


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❄❄❄ MIRROR FORMULA ❄❄❄

1/u + 1/v = 1/f

Where, we already know, "u is object distance, "v" is image distance and "f" is focal length of the spherical mirror.


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⭐⭐⭐ ALWAYS BE BRAINLY ⭐⭐⭐

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