A circuit with a battery, a 3 Ω resistor, and a 15 Ω resistor, in parallel. The total current is the system is 3.0 A. What is the voltage of the battery?

Respuesta :

Given data:

* The current through the system is I = 3 A.

* The resistance of resistors connected in parallel is,

[tex]\begin{gathered} R_1=3\text{ ohm} \\ R_2=15\text{ ohm} \end{gathered}[/tex]

Solution:

The equivalent resistance of the system is,

[tex]\frac{1}{R_{eq}}=\frac{1}{R_1}+\frac{1}{R_2}[/tex]

Substituting the known values,

[tex]\begin{gathered} \frac{1}{R_{eq}}=\frac{1}{3}+\frac{1}{15} \\ \frac{1}{R_{eq}}=\frac{5+1}{15} \\ \frac{1}{R_{eq}}=\frac{6}{15} \end{gathered}[/tex]

By taking inverse value,

[tex]\begin{gathered} R_{eq}=\frac{15}{4} \\ R_{eq}=3.75\text{ ohm} \end{gathered}[/tex]

According to Ohm's law, the voltage across the battery is,

[tex]V=IR_{eq}[/tex]

Substituting the known values,

[tex]\begin{gathered} V=3\times3.75 \\ V=11.25\text{ volts} \end{gathered}[/tex]

Thus, the voltage across the battery is 11.25 volts.