Physics
Grade-9
Easy
Question
The length of a certain conductor of resistance 50 ohm is doubled, and its cross-sectional area is halved. Its new resistance is ____.
- 100
- 50
- 200
- 400
Hint:
The correct answer is: 200
Let,
the original length be l
original area be A
Given,
original resistance = 50 
new length = l2 = 2l
new area = A2 = 
We know,
Original resistance = R = 
new resistance = R2 = 
R2 = 4 x R
R2 = 4 x 50
R2 = 200 ohm
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