Year 9 Science · Unit 3 · Lesson 19

Ohm's Law

Foundation Worksheet

Name

Date

Class

Learning Goals

State Ohm's Law and its three rearrangements: V = IR, I = V/R, R = V/I.
Use the formula to find a missing value when given two known quantities.
Distinguish between ohmic and non-ohmic conductors.

Warm Up

Match each term to its definition

Part A, Match each Ohm's Law rearrangement to what it calculates. Write the letter next to the formula.

Formula	Your answer	What it calculates
V = I × R		A. The current (in amps) when you know voltage and resistance
I = V ÷ R		B. The resistance (in ohms) when you know voltage and current
R = V ÷ I		C. The voltage (in volts) when you know current and resistance

Worked example, fill the table

Part B, Complete the missing values. Use V = IR (or its rearrangements) to find the blank cell in each row. Show your working in the space provided.

Voltage (V)	Current (I)	Resistance (R)
12 V		4 Ω
6 V	2 A
	3 A	10 Ω
240 V		48 Ω

Your Turn

True or False? Fix the false ones

Circle T or F for each statement about Ohm's Law. If the statement is false, rewrite it correctly on the line below.

Increasing resistance increases current for the same voltage.

Correct it:

V = IR means voltage equals current multiplied by resistance.

Correct it:

A light bulb filament is an ohmic conductor.

Correct it:

Doubling the voltage doubles the current if resistance stays constant.

Correct it:

Show What You Know

1. What is the unit for each of the following? Voltage: ________ Current: ________ Resistance: ________ What do the letters V, I, and R stand for in Ohm's Law?

Recall 2 marks

2. Describe the difference between an ohmic conductor and a non-ohmic conductor. Give one example of each.

Recall 2 marks

Wrap Up

In one sentence, what was the main idea of this lesson?