Physics, asked by bindu42002, 1 year ago

12) Two students A and B observed the image of a candle flame using a spherical lens of focal length
10cm. Student A observed an inverted magnified image on a screen placed 25cm on the other side
of the lens and student B observed an inverted image of the same size on the screen. What should
be their corresponding object distances? Draw ray diagram to show the image formation by
student A or B.

Answers

Answered by prmkulk1978

Student A:
f=10cms
v=25cm
object distance=?
by lens formula
1/f =1/V- 1/u
1/u = 1/v-1/f
=1/25 -1/10
=2-5/50
=-3/50
u=-50/3
=-16.6cms

student B:
f=10cms
v=20cms
object distance=?
by lens formula
1/f=1/v-1/u
1/u =1/v-1/f
=1/20-1/10
1/u=1-2/20
=-1/20
u= -20cms
object is placed on C and image is formed On C.
refer attachment for ray diagram

Attachments:

prmkulk1978: image is placed on C. same size they said. so R =2f

akshaykumaar: So r will be 20

akshaykumaar: How is that v equals 20

prmkulk1978: image we get at c which is at a distance 20cm

akshaykumaar: After taking v equals only u get that object is at c

akshaykumaar: But r is not equal to v

prmkulk1978: how do you measure v.

prmkulk1978: distance between lens and screen

prmkulk1978: so here student B observes inverted image of same size. which implies it is at C.

prmkulk1978: hence v=20

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