Question

A 238-ohm lamp, a 125-ohm lamp, and a 311-ohm lamp are connected in series and placed across a potential difference of 99.3 volts.a. What is the equivalent resistance of the circuit? Include units in your answer.b. What is the current through the 238-ohm lamp? Include units in your answer.c. What is the voltage drop across the 125-ohm lamp? Include units in your answer.

Answer 1

Given:

The resistances R1 = 238 ohm, R2 = 125 ohm, and R3 =311 ohm are connected in series across the potential difference.

To find

(a) Equivalent resistance of the circuit.

(b) Current through R1.

(c) Voltage drop across R2.

Explanation:

(a) The equivalent resistance in the circuit is

$\begin{gathered} R_{eq}=R1+R2+R3 \\ =\text{ 674 ohm} \end{gathered}$

In a series circuit, the current through the circuit will be same.

(b)The current through the resistance R1 will be

$\begin{gathered} I=\frac{V}{R_{eq}} \\ =\frac{99.3}{674} \\ =0.147\text{ A} \end{gathered}$

(c) The voltage drop across R2 will be

$\begin{gathered} V=IR2 \\ =0.147\times125 \\ =18.375\text{ V} \end{gathered}$

Final Answer

(a) Equivalent resistance of the circuit is 674 ohm.

(b) Current through R1 is 0.147 A.

(c) Voltage drop across R2 is 18.375 V.