Math Problem Statement

Consider the three resistors R1 = 23 Ω, R2 = 32 Ω, and R3 = 82 Ω in the configuration R1 then R2 and R3 in parallel. A potential difference ΔV = 7.5 V is applied between A and B. Calculate the numerical value of I2 traveling through the resistor R2, in amperes.

Solution

To solve for the current I2I_2 traveling through resistor R2R_2, we need to break the circuit down into its components and apply Ohm's Law and the rules for resistors in series and parallel.

Step 1: Analyze the circuit

  • Resistor R1R_1 is in series with the parallel combination of R2R_2 and R3R_3.
  • Resistors R2R_2 and R3R_3 are in parallel, so we first need to calculate their combined resistance.

Step 2: Calculate the equivalent resistance of R2R_2 and R3R_3 in parallel

The formula for the total resistance of two resistors in parallel is:

1Req, parallel=1R2+1R3\frac{1}{R_{\text{eq, parallel}}} = \frac{1}{R_2} + \frac{1}{R_3}

Substituting the values of R2=32ΩR_2 = 32 \, \Omega and R3=82ΩR_3 = 82 \, \Omega:

1Req, parallel=132+182\frac{1}{R_{\text{eq, parallel}}} = \frac{1}{32} + \frac{1}{82}

First, calculate the sum of the fractions:

132+182=82+3232×82=1142624\frac{1}{32} + \frac{1}{82} = \frac{82 + 32}{32 \times 82} = \frac{114}{2624}

Now, calculate the reciprocal to find the equivalent resistance:

Req, parallel=262411423.03ΩR_{\text{eq, parallel}} = \frac{2624}{114} \approx 23.03 \, \Omega

Step 3: Calculate the total resistance of the circuit

Now, we add the resistance R1=23ΩR_1 = 23 \, \Omega in series with the parallel combination:

Rtotal=R1+Req, parallel=23+23.03=46.03ΩR_{\text{total}} = R_1 + R_{\text{eq, parallel}} = 23 + 23.03 = 46.03 \, \Omega

Step 4: Calculate the total current in the circuit

Next, apply Ohm's Law to find the total current ItotalI_{\text{total}} in the circuit. The potential difference ΔV=7.5V\Delta V = 7.5 \, \text{V} is applied across the total resistance:

Itotal=ΔVRtotal=7.546.030.163AI_{\text{total}} = \frac{\Delta V}{R_{\text{total}}} = \frac{7.5}{46.03} \approx 0.163 \, \text{A}

Step 5: Calculate the current through R2R_2

Since R2R_2 and R3R_3 are in parallel, the voltage across both resistors is the same. We can use the current division rule to find I2I_2, the current through R2R_2:

I2=Itotal×R3R2+R3I_2 = I_{\text{total}} \times \frac{R_3}{R_2 + R_3}

Substituting the known values:

I2=0.163×8232+82=0.163×821140.116AI_2 = 0.163 \times \frac{82}{32 + 82} = 0.163 \times \frac{82}{114} \approx 0.116 \, \text{A}

Thus, the current through resistor R2R_2 is approximately 0.116 A.


Would you like further details on any part of the process? Here are 5 related questions to explore further:

  1. How does the current division rule work in parallel circuits?
  2. What would happen if R2R_2 and R3R_3 were in series instead of parallel?
  3. How do you calculate power dissipated by each resistor in this circuit?
  4. How would the current through R2R_2 change if R3R_3 were much smaller than R2R_2?
  5. How can we verify the current through R2R_2 using Kirchhoff's current law?

Tip: When solving circuits with resistors in series and parallel, always simplify the circuit step by step—first calculate equivalent resistances, then apply Ohm's Law to find currents and voltages.

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Math Problem Analysis

Mathematical Concepts

Ohm's Law
Series and Parallel Circuits
Current Division Rule

Formulas

Ohm's Law: V = IR
Parallel Resistance: 1 / Req = 1 / R1 + 1 / R2
Total Resistance in Series: Rtotal = R1 + R2
Current Division Rule: I2 = Itotal * (R3 / (R2 + R3))

Theorems

Ohm's Law
Kirchhoff's Current Law

Suitable Grade Level

Grades 10-12