JEE MAIN - Physics (2020 - 2nd September Morning Slot - No. 2)
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A spherical mirror is obtained as shown in the
figure from a hollow glass sphere. If an object
is positioned in front of the mirror, what will be
the nature and magnification of the image of
the object? (Figure drawn as schematic and not to scale)
Inverted, real and unmagnified
Inverted, real and magnified
Erect, virtual and magnified
Erect, virtual and unmagnified
توضیح
f = $$ - {8 \over 2}$$ = -4 cm
u = –10 cm
v = ?
Using mirror formula
$${1 \over v} + {1 \over u} = {1 \over f}$$
$$ \Rightarrow $$ $${1 \over v} + {1 \over { - 10}} = {1 \over { - 4}}$$
$$ \Rightarrow $$ v = $${{ - 20} \over 3}$$
m = $${{ - \left( { - {{20} \over 3}} \right)} \over { - 10}}$$ = $$ - {2 \over 3}$$
So image would be real, inverted and smaller than object.
u = –10 cm
v = ?
Using mirror formula
$${1 \over v} + {1 \over u} = {1 \over f}$$
$$ \Rightarrow $$ $${1 \over v} + {1 \over { - 10}} = {1 \over { - 4}}$$
$$ \Rightarrow $$ v = $${{ - 20} \over 3}$$
m = $${{ - \left( { - {{20} \over 3}} \right)} \over { - 10}}$$ = $$ - {2 \over 3}$$
So image would be real, inverted and smaller than object.