Physics, asked by Mrsaurabhjha, 1 year ago

solve question 9 and 10

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Answered by shreya0x0
1

Here's your answer...

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shreya0x0: can you tell me the correct answer?
Mrsaurabhjha: why not
masoomptl: shreya .. from where did u get v - 15 cm ? it is not given ! Focal length is given with the help of which , u have to find v
shreya0x0: which question are you talking about??
shreya0x0: i have answered the 10th one not the 9th
Mrsaurabhjha: ohh sorry
shreya0x0: Its okay...
Mrsaurabhjha: you are right
masoomptl: my bad , sorry .. u were talking abt 10 ? then only the sign is wrong
Mrsaurabhjha: ok
Answered by masoomptl
1

9 .  GIVEN ,

        Height object (ho) = 2.5 cm

             Object dist. ( u ) = -25 cm

               Focal length (f) =-20cm             v=?

           therefore , 1/f = 1/u+1/v

                          1/v = 1/u-1/f

                          1/v  = 1/-25+1/-20

                                 = (-20)+(-25)/500  

                                  = 45/500

                                 = 1/11.1

                     therefore , v=11.1 cm

MAGNIFICATION = height of image/height of object = -v/u

                             =hi/2.5=-11.1/-25

                              cross multiplication ...

                              27.75 = hi*25

                               hi = 1.1 cm

therefore ... Image is virtual , erect and diminished ...

                         

10.  GIVEN ,

    U = -20 cm

     V = - 15 cm

f= ?

1/f = 1/u+1/v

     = 1/-15 + 1/-20

     = (-15)+(-20)/-15*-20

     = -35/300

   = -8.57 cm

Since focal length is -ve ..... the mirror is concave .


Mrsaurabhjha: right answer
masoomptl: Thankyou
masoomptl: i have added 10th
Mrsaurabhjha: ok
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