Resistance of A System of Resistors: Series and Parallel

Content Standards

In this lesson, students will understand how resistors combine in series and parallel, how to compute net resistance (Rnet ), and how Ohm’s law applies to each configuration. They interpret current/voltage distribution (same current in series, same voltage in parallel) and solve numerical problems with a fixed source voltage.

Performance Standards

Students will be able to:

Determine Rnet for series and parallel combinations.
Apply V = IR to find unknown I, V, or R.
Explain current continuity in series and voltage equality in parallel.
Justify design choices (when series vs parallel is suitable).

Alignment Standards

Reference: NCERT Book Alignment

The lesson is aligned with the NCERT Grade 10 Science Textbook, Chapter 11: Electricity, Section 11.6 Resistance of a System of Resistors.

Learning Objectives

By the end of the lesson, students will be able to:

Compute Rnet for given series/parallel sets.
Use I = V / Rnet with a fixed source (e.g., 5 V).
Predict current/voltage sharing in series vs parallel.
Check answers by estimating limits

Prerequisites (Prior Knowledge)

Understanding of electric circuits, including charge, current, voltage, and resistance, as well as their unit symbols.
Familiarity with Ohm’s Law (V = IR) and its application.
Basic algebra skills, including working with fractions and reciprocals.

Introduction

In this session, students will learn how series and parallel resistor configurations affect total resistance, current, and voltage distribution, enabling them to predict and control circuit behavior using Ohm’s law.

Timeline (40 Minutes)

Title	Approximate Duration	Procedure	Reference Material
Engage	5	Ask: “What happens when resistors are connected in a circuit? How does the current behave in each situation?”	Slides
Explore	10	Explain what is resistor to the students and recall all the basic conmcept of electricity.	Slides
Explain	10	Explain Resistors in series and parallel connection with the help of circuit diagram and mathematical equation for both of them.	Slides + Virtual Lab
Evaluate	10	Students will attempt the Self Evaluation task on LMS.	Virtual Lab
Extend	5	Calculate the value of resistor in the given circuit.	Slides

Resistance of A System of Resistors: Series and Parallel

Introduction

In this session, you will explore how resistors combine in series and parallel, how to calculate net resistance, and how current and voltage share in each case. They will use Ohm’s law to predict circuit behavior with a fixed supply.

Theory

Why learn this?

Home wiring uses parallel so each appliance gets full mains voltage.
A torch often uses cells in series; combinations control current and brightness.

This leads to understanding series vs parallel connections and how to find Rnet to apply Ohm’s Law confidently.

What is the concept?

A resistor network is a group of resistors connected together. The net (equivalent) resistance Rnet is the single resistance that would draw the same current from the source as the whole network.

Key components:

Series: one current path; same current through every resistor; voltages add.
Parallel: multiple branches; each branch is across the source; currents add.
Ohm’s Law: V = IR applies to the whole network or an individual element.

Steps

Series (one current path)

Identify a single loop with resistors end-to-end.
Rnet = R1 + R2 + R3 + …
Current same; voltage adds; check Rnet > any part.

Parallel (branches)

Identify branches between the same two nodes.
1/Rnet = 1/R1 + 1/R2 + 1/R3 + …
Voltage same; currents add; check Rnet < smallest branch.

Applications / Why is it useful?

Home wiring in parallel so one device off does not stop others.
Current limiting and sensing with series resistors.
Power management by controlling total current and heat.

Vocabulary

This is the list of vocabulary terms used throughout the lesson.

Net (equivalent) resistance Rnet: Single resistance that replaces a network while drawing the same current from the source.
Series connection: Components one after another in a single path; same current; voltages add.
Parallel connection: Components across the same two nodes; same voltage; currents add.
Voltage drop: Potential difference across a component, V = IR.
Branch current: Current flowing in a parallel path.
Ohm’s Law V = IR: Relation linking voltage, current, and resistance.

Resistance of A System of Resistors: Series and Parallel

Introduction

In this VR lab you will switch between Series and Parallel, set R1, R2, R3 with sliders, and see Rnet and current I update live using Ohm’s law with a fixed 5 V source.

Key Features

Mode Tabs: Series / Parallel.
Value Sliders: set R1, R2, R3 (1–20 Ω).
Live Rnet & I Calculator: updates as you drag.
Branch meters (parallel) and voltage drops (series).
Reset / Randomise practice sets.
Quiz Dock (2 MCQs).

Step-by-Step Procedure for VR Experience

Step-by-step Procedure for VR Experience

1) Start & Overview

Open the lab and read the short overview explaining series (one path) and parallel (branches).
Note that you will compare net resistance, current, and voltage sharing in each mode.

2) Series Mode (one continuous path)

Select Series mode.
Set the three resistor values using the sliders (for example: three small numbers to begin).
Watch the net resistance display: in series it increases as you add more resistance in line.
Observe the current reading: as the net resistance becomes larger, the current becomes smaller for the same supply.
Open the voltage drop view: you will see the supply voltage shared across the resistors in line.
Change one slider at a time and notice how:
- Net resistance goes up when any single resistor value is raised.
- Current goes down when the net resistance goes up.
- Voltage drops across each resistor adjust but still add up to the supply.

3) Parallel Mode (separate branches)

Switch to Parallel mode.
Set the three resistor values using the sliders (start with one small and two larger values).
Watch the net resistance display: in parallel it becomes smaller as you add more branches or reduce a branch value.
Observe the current readings:
- The total current from the source is the sum of branch currents.
- Each branch has the same voltage across it as the source.
Change one slider at a time and notice how:
- Lowering any single branch value makes the total current rise.
- The branch with the smallest resistance draws the largest current.
- The net resistance stays below the smallest single branch value.

4) Explore & Compare (concept checks)

Predict before you slide: say aloud whether net resistance and current will rise or fall, then check the meters.
Try these quick tests:
- Series test: increase one resistor value and observe less current.
- Parallel test: add a low-resistance branch and observe more total current.
Save two screenshots or jot two examples with your observations in full sentences.

5) Quick Self-Check

In Series, explain in one sentence why the same current flows through all resistors.
In Parallel, explain in one sentence why each branch has the same voltage as the source.
State which set-up you would choose to let one device switch off without affecting the others (and why).

6) Mini-Quiz

Open the quiz panel and answer the two questions