Question

A student in the laboratory connects a 20 Ω resistor, a 30 Ω resistor, and a 42 Ω resistor in series and then connects the arrangement to a 65-V dc source.(a) How much current is in the circuit? ________:A(b) How much power is expended in the circuit? _________:W

Answer 1

First, let's calculate the equivalent resistance of the three series resistances:

$\begin{gathered} R_{eq}=R_1+R_2+R_3\\ \\ R_{eq}=20+30+42\\ \\ R_{eq}=92\text{ \Omega} \end{gathered}$

(a)

To calculate the current in the circuit, we can use Ohm's Law:

$\begin{gathered} I=\frac{V}{R}\\ \\ I=\frac{65}{92}\\ \\ I=0.7065\text{ A} \end{gathered}$

(b)

To calculate the power expended in the circuit, we can use the formula below:

$\begin{gathered} P=I\cdot V\\ \\ P=0.7065\cdot65\\ \\ P=45.92\text{ W} \end{gathered}$