Lesson 2: Ohm's Law

Open Ended

Imagine you have a resistor in a circuit powered by a single 3 V battery.

Predict what would happen to the current in the circuit if you replaced the 3 V battery with a 6 V battery. Explain your answer.

Open Ended

You then remove the battery from the circuit and connect the wires together.

Determine how much current will flow. Explain your answer. 

Multiple Choice

Who was Georg Ohm and what was his contribution to the study of electricity?

• He invented the light bulb

• He discovered the relationship between current, voltage, and resistance

• He created the first battery

• He discovered electromagnetic induction

Multiple Choice

According to the relationship I = mV, what happens to the current if the voltage is doubled while the gradient (m) remains constant?

• The current is halved

• The current remains the same

• The current is doubled

• The current becomes zero

Multiple Choice

A circuit with a 9 V battery has a current of 3 A.

Calculate how much current would flow if the same circuit was powered by a 3 V battery. 

• 0.3 A

• 1 A

• 3 A

• 9 A

Multiple Choice

Which of the following statement IS NOT correct about the effect of resistance on current at constant voltage?

• Doubling resistance halves the current

• Current is inversely proportional to resistance

• Current is directly proportional to resistance

• Resistance must be measured in ohms

Draw

The circuit in a particular walkie-talkie has a total resistance of 450 Ω and the battery is supplying 9 V.

Calculate how much current, in amps (A), is flowing. 

(Solve the question in the blank canvas)

Draw

You have a red LED that you want to connect to a 12 V battery. The maximum current that it's safe to put through this LED is 10 mA.

Calculate how much resistance the circuit needs. 

Hint: Remember that there are 1000 mA in 1 A.

(Solve the question in the blank canvas)

Draw

You've been given a new robot for Christmas! The total resistance of its internal circuitry is 900 Ω and the current it requires is 5 mA.

Calculate how many 1.5 V batteries it will need to operate. 

Hint: Remember that there are 1000 mA in 1 A.

(Solve the question in the blank canvas)

Open Ended

What questions do you still have about Ohm's law or its applications in real-world circuits?