find the focal lenght of the convave mirror that produces four times real image of an object held 5 cm from the mirror
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Answer:
We know that,
The magnification is
m=-\dfrac{v}{u}
4=-\dfrac{v}{5}
v = -20 cm
Using mirror formula
\dfrac{1}{f}=\dfrac{1}{v}+\dfrac{1}{u}
\dfrac{1}{f}=\dfrac{1}{-20}+\dfrac{1}{-5}
\dfrac{1}{f}=\dfrac{-5}{20}
\dfrac{1}{f}=-\dfrac{1}{4}
f= -4\ cm
Explanation:
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