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Grade 10General Physics

Find the effective resistance between A and B and please tell the process to solve

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Profile image of Rajib kumar
5 Years agoGrade 10
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1 Answer

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ApprovedApproved Tutor Answer11 Months ago

To find the effective resistance between two points A and B in a circuit, we need to analyze how the resistors are arranged—whether they are in series, parallel, or a combination of both. Let’s break down the process step by step.

Understanding Resistor Configurations

Resistors can be connected in two primary ways:

  • Series Connection: In a series circuit, the current flows through each resistor one after the other. The total resistance (R_total) is simply the sum of the individual resistances.
  • Parallel Connection: In a parallel circuit, the current can flow through multiple paths. The total resistance can be calculated using the formula: 1/R_total = 1/R1 + 1/R2 + 1/R3 + ...

Step-by-Step Process

Let’s go through the steps to find the effective resistance between points A and B:

1. Identify the Configuration

First, look at the circuit diagram and identify how the resistors are connected. Are they in series, parallel, or a combination? This will dictate how you calculate the total resistance.

2. Calculate Series Resistances

If the resistors are in series, use the formula:

R_total = R1 + R2 + R3 + ...

For example, if you have three resistors of 2Ω, 3Ω, and 5Ω in series, the total resistance would be:

R_total = 2 + 3 + 5 = 10Ω

3. Calculate Parallel Resistances

If the resistors are in parallel, apply the parallel resistance formula:

1/R_total = 1/R1 + 1/R2 + 1/R3 + ...

For instance, if you have two resistors of 4Ω and 6Ω in parallel, the calculation would be:

1/R_total = 1/4 + 1/6

Finding a common denominator (12), we get:

1/R_total = 3/12 + 2/12 = 5/12

Thus, R_total = 12/5 = 2.4Ω

4. Combine Series and Parallel

In many circuits, you will encounter a combination of series and parallel resistors. In such cases, simplify the circuit step by step:

  • Start by calculating the total resistance of the parallel groups.
  • Then, add the series resistances.
  • Repeat this process until you reduce the circuit to a single equivalent resistance between points A and B.

Example Problem

Imagine a circuit where you have two resistors, 4Ω and 6Ω, in parallel, and this combination is in series with a 5Ω resistor. Here’s how you would solve it:

  1. Calculate the parallel resistors: 1/R_parallel = 1/4 + 1/6 = 5/12 so, R_parallel = 12/5 = 2.4Ω
  2. Add the series resistor: R_total = R_parallel + R_series = 2.4 + 5 = 7.4Ω

Thus, the effective resistance between points A and B is 7.4Ω.

Final Thoughts

By following these steps and understanding the configurations, you can effectively determine the resistance in various circuit setups. Practice with different combinations to strengthen your grasp on the topic!