Question 14:
Compare the power used in the 2 Ω resistor in each of the following circuits: (i)
a 6 V battery in series with 1 Ω and 2 Ω resistors, and (ii) a 4 V battery in parallel
with 12 Ω and 2 Ω resistors.
Answer:
(i) Potential difference, V = 6 V
1 Ω and 2 Ω resistors are connected in series. Therefore, equivalent resistance of
the circuit, R = 1 + 2 = 3 Ω
According to Ohm’s law,
V = IR
Where,
I is the current through the circuit
This current will flow through each component of the circuit because there is no
division of current in series circuits. Hence, current flowing through the 2 Ω resistor
is 2A.
Power is given by the expression,
P=(I)2R = (2)2 × 2 = 8 W
(ii) Potential difference, V = 4 V
12 Ω and 2 Ω resistors are connected in parallel. The voltage across each component
of a parallel circuit remains the same. Hence, the voltage across 2 Ω resistor will be
4 V.
Power consumed by 2 Ω resistor is given by
Therefore, the power used by 2 Ω resistor is 8 W.
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