Lesson 2: Electrical Circuits

In the figure on the right, you can see the movement of the electrons is constantly occurring in the wire. The constant flow of electrons allows for constant powering of the lightbulb.

Voltage, Current and Resistance

Voltage

The electrical pressure in the circuit.
It is measured in Volts (V)

Current

The rate of movement of particles in a circuit.
Measured in Ampere (A)

Resistance

The property of materials to oppose the flow of particles.
Measured in Ohm’s (Ω)

These variables share a mathematical relationship, where one can be determined from the other two.

This is called Ohm’s Law

Basic Circuits

A circuit is the path of current electricity though different wires and components.

We use circuit diagrams to represent them.

We use special symbols to represent different parts of a circuit like batteries, lights, wires and switches

In the figure on the left, two drawings of the same circuit. One using the circuit diagram method (top) and the other a drawing of each of the parts of a circuit (bottom).

Activities

Circuits Electricity Simulations

Try some of these simulations for static electricity:

https://phet.colorado.edu/en/simulations/ohms-law
- Investigate the relationship of Ohm's Law, then answer these questions.
  1. As voltage increases but resistance stays the same what happens to current?
    What type of mathematical relationship is this?
    Why does this occur?
  2. If you keep voltage consistent but increase resistance what happens to current?
    What type of mathematical relationship is this?
    Why does this occur?
  3. In the circuit, how is the current being increased? (What is being added to the circuit?)
  4. If you have a circuit with 4.5V and a lightbulb with a resistance of 80Ω what will the Current be (in mA)? Show your working.
  5. If the voltage is still 4.5Vby the current is now 5.8 mA what is the resistance be (in Ω)?

https://phet.colorado.edu/en/simulations/circuit-construction-kit-dc
- Using this kit begin to set up a basic circuit. Experiment for a while build your own circuit. Then move on to the questions in this document.

Circuits Simulation

Static Electiricy Simulations Answers

Ohm's Law Simulation

As resistance increases the current decreases.
They have a inverse realtionship, this meaning as one increases the other decreases. This is due to the electrons having a harder time getting through the circuit.
Current increases as voltage increases.
They have a direct realtionship, meaing as one increases so does the other.
This is due to the increased pressure on the electrons in the circuit wanting to move through the circuit, this increases the rate or current.
More batteries are being added.
V=RxI
V=4.5V, R=80Ω
Rearrange for I
I=V/R
I=4.5V/80Ω=0.05625 A
Convert to mA
=0.05625A*1000
=56.25mA
V=RxI
V=4.5V, I=5.8mA
Convert to A
=5.8mA/1000
=0.0058A
Rearrange equation for R
R=V/I
=4.5V/0.0058A
=775.86Ω

Circuits Simulation

Answers to the right->

Answers for Circuits Simulation

Reflection

Written Reflection

What did you struggle with?
What was really easy?
What are you still curious about?

Success Criteria

Which level are you currently sitting at in the success criteria? (see images below).

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