The converging lens below has a focal length of 10 cm. At which point (P), (Q), (R) or (S) in front of the converging lens should an object be placed to obtain a virtual, magnified image?
Answers
Explanation:
(a) f=10cm
v=20cm (real image)
v
1
+
u
1
=
f
1
−20
1
+
u
1
=
−10
1
u
1
=
10
−1
+
20
−1
=
20
−1
u=−20cm
(b)f=10cm
v=20cm (virtual image)
v
1
+
u
1
=
f
1
20
1
+
u
1
=
−10
1
u
1
=
10
−1
+
20
−1
=
20
−3
u=−
3
20
cm
Answer:
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Class 12
>>Physics
>>Ray Optics and Optical Instruments
>>Mirror Formula and Magnification
>>At what distance from a con...
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At what distance from a concave mirror of focal length 10cm should an object be placed so that:
(a) its real image is formed 20 cm from the mirror?
(b) its virtual image is formed 20cm from the mirror?
Medium
Solution
verified
Verified by Toppr
(a) f=10cm
v=20cm (real image)
v
1
+
u
1
=
f
1
−20
1
+
u
1
=
−10
1
u
1
=
10
−1
+
20
−1
=
20
−1
u=−20cm
(b)f=10cm
v=20cm (virtual image)
v
1
+
u
1
=
f
1
20
1
+
u
1
=
−10
1
u
1
=
10
−1
+
20
−1
=
20
−3
u=−
3
20
cm