Two circuits have identical voltage sources. The only other elements in the circuits are resistors. The resistor in circuit [tex]\(A\)[/tex] has a resistance that is one half as large as the resistance of the resistor in circuit [tex]\(B\)[/tex] [tex]\(\left(R_A = \frac{1}{2} R_B\right)\)[/tex].

Which statement below best describes the current flowing through the two circuits? (Ohm's law: [tex]\(V = IR\)[/tex])

A. The current flowing through circuit [tex]\(A\)[/tex] is [tex]\(\frac{1}{2}\)[/tex] as large as the current flowing through circuit [tex]\(B\)[/tex].

B. The current flowing through circuit [tex]\(A\)[/tex] is 4 times as large as the current flowing through circuit [tex]\(B\)[/tex].

C. The current flowing through circuit [tex]\(A\)[/tex] is 2 times as large as the current flowing through circuit [tex]\(B\)[/tex].

D. The current flowing through circuit [tex]\(A\)[/tex] is [tex]\(\frac{1}{4}\)[/tex] as large as the current flowing through circuit [tex]\(B\)[/tex].



Answer :

To determine the relation between the currents in circuits [tex]\( A \)[/tex] and [tex]\( B \)[/tex], we can proceed with the following steps:

1. Identify given values:
- Both circuits have identical voltage sources, so we can denote the voltage [tex]\( V \)[/tex] the same for both circuits.
- The resistor in circuit [tex]\( A \)[/tex] has a resistance [tex]\( R_A \)[/tex] which is half of the resistance [tex]\( R_B \)[/tex] in circuit [tex]\( B \)[/tex]. This gives us the equation:
[tex]\[ R_A = \frac{1}{2} R_B \][/tex]

2. Apply Ohm's Law:
- Ohm's Law states that [tex]\( V = I \cdot R \)[/tex]. We can solve this for current ([tex]\( I \)[/tex]):
[tex]\[ I = \frac{V}{R} \][/tex]

3. Calculate the currents in each circuit:
- For circuit [tex]\( A \)[/tex]:
[tex]\[ I_A = \frac{V}{R_A} \][/tex]
- For circuit [tex]\( B \)[/tex]:
[tex]\[ I_B = \frac{V}{R_B} \][/tex]

4. Express [tex]\( R_A \)[/tex] in terms of [tex]\( R_B \)[/tex]:
Since [tex]\( R_A = \frac{1}{2} R_B \)[/tex], substitute this into the equation for [tex]\( I_A \)[/tex]:
[tex]\[ I_A = \frac{V}{\frac{1}{2} R_B} = \frac{2V}{R_B} \][/tex]

5. Find the ratio of [tex]\( I_A \)[/tex] to [tex]\( I_B \)[/tex]:
- We already know that:
[tex]\[ I_B = \frac{V}{R_B} \][/tex]
- To compare [tex]\( I_A \)[/tex] and [tex]\( I_B \)[/tex], we take the ratio:
[tex]\[ \frac{I_A}{I_B} = \frac{\frac{2V}{R_B}}{\frac{V}{R_B}} = \frac{2V}{R_B} \times \frac{R_B}{V} = 2 \][/tex]

This shows that the current in circuit [tex]\( A \)[/tex] is 2 times the current in circuit [tex]\( B \)[/tex]. Therefore, the correct statement is:

C. The current flowing through circuit [tex]\( A \)[/tex] is 2 times as large as the current flowing through circuit [tex]\( B \)[/tex].