Question

Please answer it

Appropriate answer will be marked as BRAINLIEST ✌️​

Answer 1

m= -2/3 = v/u

u= -12

-2/3 = v/-12

v= 8


f = uv)/(u-v)

f= -12(80)/( -12 -8)


f= 960 /20 = 48

Answer 2

Answer:-

➣

$\bf{f = 7.2 \: cm}$

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Size of the image = $\large \frac{-2}{3}\times$ size of object.

or

Magnefication= $\large \frac{Size \: of \: image}{Size \: of \: object}$=$\bf{\large \frac{v}{u}}$

or

$\large \frac{-2}{3}$ = $\large \frac{v}{u}$

$\implies \large{ u = [\frac{-3}{2}v]}$

$\implies \bf{u = -1.5v}$$\: \: \: \: \: \longrightarrow[1]$

Image distance [v] = $\bf{12 \: cm}$

Object distance [u] = $-1.5v = -1.5 \times 12$

$\implies \bf{-18 \: cm}$

• Using the formula:-

$\bf \boxed{\frac{1}{v}-\frac{1}{u} = \frac{1}{f}}$

$\longrightarrow\large{\frac{1}{12}-\frac{1}{-18} = \frac{1}{f}}$

$\longrightarrow\large{\frac{1}{12} + \frac{1}{18} = \frac{1}{f}}$

$\longrightarrow\large{\frac{5}{36} = \frac{1}{f}}$

Therefore,

$f = \large \frac{36}{5}$

$f = \large \cancel{\frac{36}{5}}$

$\large \bf{f = 7.2 \:cm}$

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