Question

plz answer this question its very imp.

Answer 1

Sorry friend I try to solve it but I can't I hope any other user will definitely help u

Answer 2

m = $\frac{v}{u}$ = -1

     v = -u                ...................(a)

     v-u = 60 { distance b/w image and object }..................(1)

     put (a) in (1)

 ∴  -u-u = 60cm

    -2u = 60cm

     -u = 30cm

      u = -30cm  (put in (a))

     v = - (-30)

     v = 30cm

∵ lens formula  

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

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

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

$\frac{2}{30} = \frac{1}{f}$

$\frac{30}{2} = f$

    15cm  = f

$u_{2}$ = -10cm ( new object distance )

∴   $\frac{1}{v_{2}} - \frac{1}{u_{2}} = \frac{1}{f}$      f is always same

$\frac{1}{v_{2}} = \frac{1}{f} +\frac{1}{u_{2}}$

$\frac{1}{v_{2}} = \frac{1}{15} +\frac{1}{-10}$

$\frac{1}{v_{2}} = \frac{1}{15} -\frac{1}{10}$

$\frac{1}{v_{2} } = \frac{2-3}{30}$

$\frac{1}{v_{2}} = \frac{-1}{30}$

$v_{2} = -30 cm$