High School

A circuit includes a 3 V bulb, a 12-ohm resistor, and a 9 V battery. Another circuit is provided that does not include the 12-ohm resistor. The resistance of the bulb is 6 ohms. In which circuit is the potential difference of 3 V present?

Answer :

The potential difference of 3 V occurs in the circuit with the 12-ohm resistor.

To determine in which circuit the bulb experiences a potential difference of 3 V, we need to analyze both circuits step-by-step.

Circuit 1:

  • It has a 9 V battery and a 12-ohm resistor connected in series with the 6-ohm bulb.

  • The total resistance in the circuit can be calculated as:

    [tex]R_{total} = R_{bulb} + R_{resistor} = 6 \Omega + 12 \Omega = 18 \Omega[/tex]

  • According to Ohm's Law, the current (I) flowing through the circuit can be found using:

    [tex]I = \frac{V}{R} = \frac{9 V}{18 \Omega} = 0.5 A[/tex]

  • To find the potential difference (V) across the bulb, we can again use Ohm's Law, now for just the bulb:

    [tex]V_{bulb} = I \times R_{bulb} = 0.5 A \times 6 \Omega = 3 V[/tex]

Circuit 2:

  • This circuit consists only of the 9 V battery and the 6-ohm bulb without the 12-ohm resistor.

  • The total resistance in this circuit is simply the resistance of the bulb:

    [tex]R_{total} = 6 \Omega[/tex]

  • Again using Ohm's Law for the current, we find:

    [tex]I = \frac{9 V}{6 \Omega} = 1.5 A[/tex]

  • Now, to find the potential difference across the bulb:

    [tex]V_{bulb} = I \times R_{bulb} = 1.5 A \times 6 \Omega = 9 V[/tex]

Conclusion:
From our calculations, we see that in Circuit 1, the bulb receives a potential difference of 3 V, while in Circuit 2, it receives a 9 V potential difference.

Thus, the correct answer is that the potential difference of 3 V occurs in the circuit with the 12-ohm resistor.

Answer:

9 V

Explanation:

For the first circuit:

[tex]R_{total}=R+R_b=12+6=\bf18\:$\Omega$\\[/tex]

We apply Ohm's Law:

[tex]I=\frac{V}{R_{total}}=\frac{9}{18}=\frac{1}{2}=0.5\:A[/tex]

We find the voltage for the bulb:

[tex]V_b=I+R_b=0.5\times6=\bf3\:V\\[/tex]

For the second circuit:

We apply Ohm's Law:

[tex]I=\frac{V}{R_b}=\frac{9}{6}=\frac{3}{2}=1.5\:A\\[/tex]

We find the voltage for the bulb:

[tex]V_b=I\times R_b=1.5\times6=\bf9\:V[/tex]