At what distance from a concave mirror of focal length 10 centimetre should an object be placed so that 1.its real image is formed 20 cm from the mirror next
2. Its virtual image is formed 20 cm from the mirror
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Hence for case 1. u= -20 cm
for case 2. u= -20/3 cm
for case 2. u= -20/3 cm
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1. a real image 20 cm from the mirror
u=?
v=20cm
f=10cm
mirror formula states
1/f=1/v+1/u
1/10=1/20+1/u
1/u=1/10-1/20
1/u=1/20
Therefore u=20
so distance of object=20
2. the object should be placed at
v=-20cm
u=?
f=10cm
1/10=-1/20+1/u
u=20/3cm
u=?
v=20cm
f=10cm
mirror formula states
1/f=1/v+1/u
1/10=1/20+1/u
1/u=1/10-1/20
1/u=1/20
Therefore u=20
so distance of object=20
2. the object should be placed at
v=-20cm
u=?
f=10cm
1/10=-1/20+1/u
u=20/3cm
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