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UPSC CDS Science Physics Questions Part 1
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© examsnet.com
Question : 48
Total: 105
Suppose voltage V is applied across a resistance R. The power dissipated in the resistance is P. Now the same voltage V is applied across a parallel combination of three equal resistors each of resistance R. Then the power dissipated in the second case will be
[2017 CDS-I]
P
3P
P
3
2
P
3
Validate
Solution:
The power dissipated in the second case will be 3P
When one resistor is connected, the equivalent resistance is REQ = R.
So, power dissipated
=
V
2
R
=
P
.
But, if the three equal resistors are connected in parallel, the equivalent resistance is REQ
=
R
3
Power for the parallel combination is
=
3
×
(
V
2
R
)
=
3
×
P
Hence, the parallel combination dissipates 3 times the power of the simple combination
© examsnet.com
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