Question

Mela koi help karo .... please

Aul koi spam nii☺️​

Answer 1

object distance(u) = - 30 cm

( object distance of an object placed in front of mirror is always negative as distances are always measured from the pole of the mirror)

the size of the image is 3 times the size of the object

hi =-3 ho

(as the object is real the image formed must be inverted hence height of the image is negative)

we know that ,

$m = - \frac{v}{u} = \frac{hi}{ho}$

$- \frac{v}{u} = - \frac{3ho}{ho}$

$v = 3u$

$v = 3 \times - 30 = - 90cm$

As per the mirror formula,

$\frac{1}{f} = \frac{1}{v} + \frac{1}{u}$

$\frac{1}{f} = \frac{1}{ - 90} + \frac{1}{ - 30}$

$\frac{1}{f} = \frac{ - 3 - 1}{90}$

$\frac{1}{f} = \frac{ - 4}{90}$

$f = 22.5cm$

Answer 2

Answer:

object distance(u) = - 30 cm

( object distance of an object placed in front of mirror is always negative as distances are always measured from the pole of the mirror)

the size of the image is 3 times the size of the object

hi =-3 ho

(as the object is real the image formed must be inverted hence height of the image is negative)

we know that ,

m = - \frac{v}{u} = \frac{hi}{ho}m=−

u

v

=

ho

hi

- \frac{v}{u} = - \frac{3ho}{ho}−

u

v

=−

ho

3ho

v = 3uv=3u

v = 3 \times - 30 = - 90cmv=3×−30=−90cm

As per the mirror formula,

\frac{1}{f} = \frac{1}{v} + \frac{1}{u}

f

1

=

v

1

+

u

1

\frac{1}{f} = \frac{1}{ - 90} + \frac{1}{ - 30}

f

1

=

−90

1

+

−30

1

\frac{1}{f} = \frac{ - 3 - 1}{90}

f

1

=

90

−3−1

\frac{1}{f} = \frac{ - 4}{90}

f

1

=

90

−4

f = 22.5cmf=22.5cm