In the Fig above, Current I passes through the combination, if the power dissipated in the 5 ohm resistor is 40W, then the power dissipated in the 10 ohm resistor is

10W
20W
40W
80W
100W
Explanation
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Discussions (17)

Since in a parallel connection there is different current but same voltage in the circuit.
Where P1= V²/R
40 = V²/5
Then V²=200v
Since same voltage is applied
P = 200/10
P = 20W

Power Dissipated=I
2
×R
Given that the current
�
I in both resistors are different, but from
�
=
�
�
V=IR, we have
�
=
�
�
I=
R
V
.
Substituting
�
=
�
�
I=
R
V
into the previous formula, we get:
Power Dissipated
=
(
�
2
×
�
�
2
)
Power Dissipated=(
R
2
V
2
×R
)
Power Dissipated
=
�
2
�
Power Dissipated=
R
V
2
Given that
40
=
�
2
5
40=
5
V
2
in the
5
Ω
5Ω resistor, we can solve for
�
2
V
2
:
�
2
=
40
×
5
=
200
V
2
=40×5=200
�
=
200
V=
200
Then, the power dissipated in the
10
Ω
10Ω resistor is:
Power Dissipated
=
�
2
�
=
(
200
)
2
10
=
200
10
=
20
watts
Power Dissipated=
R
V
2
=
10
(
200
)
2
=
10
200
=20 watts
So, option B is correct.

Power Dissipated = I^2 x R
but the current, I in the both resistors are different but from V=IR
I = V/R
Then put in the previous formula, we should have (V^2 x R) / R^2
then 40 = V^2/5
V^2 = 200
V = √200
For the 10 ohm resistor, the power dissipated is V^2/R
= ((√200)^2)/10
= 200/10
= 20 watts
That is option B




