Physics Questions ???
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2
Solution
power of lens= 1/f (in meter)
= 100/25=+4D
__________
☺☺
power of lens= 1/f (in meter)
= 100/25=+4D
__________
☺☺
Anonymous:
I think the answer is 3D
check my answer
Answered by
12
hello friend....!!!
• Option ' A ' is the core answer!!
• Reason :
in first case it is given that, the person can't see distinctly at a distance less than one Meter, implies,
f = 1 m
P = 1 / f
P = 1 D ------------( 1 )
similarly, in second case,
we should calculate the power that should be used to read a book at distance 25cm
f = 25 cm = 0.25 m
P = 1 / f
P = 1 / 0.25
P = 4 D ------------ ( 2 )
therefore,
the power that should be used is,
P = 4D - 1 D = 3D [ subracting equation (1) from (2) ]
therefore option ' A ' +3D is the correct answer.
________________________________
hope it helps....!!!
• Option ' A ' is the core answer!!
• Reason :
in first case it is given that, the person can't see distinctly at a distance less than one Meter, implies,
f = 1 m
P = 1 / f
P = 1 D ------------( 1 )
similarly, in second case,
we should calculate the power that should be used to read a book at distance 25cm
f = 25 cm = 0.25 m
P = 1 / f
P = 1 / 0.25
P = 4 D ------------ ( 2 )
therefore,
the power that should be used is,
P = 4D - 1 D = 3D [ subracting equation (1) from (2) ]
therefore option ' A ' +3D is the correct answer.
________________________________
hope it helps....!!!
power of the lens given to the person = power of normal eye - power of convex lens
they are asking the power of lens that the person should use
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