PHYSICS

JAMB 2021 - Question 22

Physics 2021 JAMB Past Questions - Question 22:  A parallel arrangement of 3Ω and 6Ω resistors is placed in series with an 8Ω resistor. If a potential difference of 30V is connected across the whole circuit, the current in the 3Ω resistor is

Choose the correct answers from the options given.
 A parallel arrangement of 3Ω and 6Ω resistors is placed in series with an 8Ω resistor. If a potential difference of 30V is connected across the whole circuit, the current in the 3Ω resistor is
A:
B:
C:
D:
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Correct Answer

B

Explanation

To find the current flowing through the 3Ω resistor, we can use Ohm's law, which states that the current (I) flowing through a resistor is equal to the voltage (V) across the resistor divided by the resistance (R) of the resistor.

First, we need to find the equivalent resistance of the parallel arrangement of the 3Ω and 6Ω resistors. The formula for the equivalent resistance (Rp) of two resistors in parallel is:

1/Rp = 1/3Ω + 1/6Ω
1/Rp = 2/6Ω + 1/6Ω
1/Rp = 3/6Ω
1/Rp = 1/2Ω
Rp = 2Ω

Now, we can find the total resistance (Rt) of the circuit by adding the equivalent resistance of the parallel arrangement to the 8Ω resistor in series:

Rt = Rp + 8Ω
Rt = 2Ω + 8Ω
Rt = 10Ω

Now that we have the total resistance, we can use Ohm's law to find the current (I) flowing through the circuit:

I = V / Rt
I = 30V / 10Ω
I = 3A

So, the current in the 3Ω resistor is 30V / 3Ω = 10A.