Circuit Basics 101

• Physics
• Secondary Education
• Age 12

What Do You Know About Circuits?

Breadboard

• Used for testing and prototyping
• Allows components to be arranged around the board by connecting terminals to appropriate holes
• Requires a power supply

Explain the rows and columns of a breadboard, the power supply connects to either of the two sets of columns of the breadboard, positive to positive and negative to negative. 

The rows are then supplied with a current where the wire is connected, the current is stopped in the middle of the board.

How many volts do you think we need for our breadboard?

The resistance in the cables as well as the batteries not being brand new are factors as to why the voltmeter does not read 5V

That's right, 5 Volts!

We can use the tool shown in the video to calculate the voltage in a closed circuit. This is called a Voltmeter.

Now we need to power our breadboard!

What does LED stand for?

1. Less Efficient Diode
2. Light Emitting Dongle
3. Light Emitting Diode
4. Low Effect Deflector

LED

This is an LED, when a current is passing through it, light is emitted. The LED can display multiple colours and also adds very little resistance when current is flowwing in the right direction.

Connecting an LED

• LEDs have one pin that is longer than the other, this is the positive pin.
• The shorter pin must be connected to the negative end of the power supply on the breadboard.
• Red = Positive
• Black = Negative

00:10

What do you think this component is and what does it do?

Buttons in a circuit

• When pressed, complete the circuit and allow a current to flow.
• When not pressed, circuit has not been 
  closed and a current will not flow.
• The symbols in the diagram are
  - Button (left), - LED (middle)
  - 5 volt battery (right)

We use an LED in the circuit because it gives a clear sign that a current is passing through the circuit

What other component also allows control over closing a circuit?

1. Diode
2. Switch
3. Resistor
4. Capacitor

A button on a breadboard has 2 pins on either side. Current will flow from 1 pin to another on the same side

Is it possible to connect 2 LEDs to the same button on the same circuit?

1. Yes it is!
2. No it isn't!

Can we make multiple circuits on the same breadboard?

Yes we can.

On the same breadboard we can create multiple circuits that are unaffected by one another.

The power supply powers an entire column of the breadboard which can be used!

Which of these is a potentiometer?

1. 
2. 
3. 

00:24

What will happen when we twist the top of the potentiometer?

That's right!

A Potentiometer is also called a variable resistor.

The name says it all, this component allows us to vary the resistance within the circuit.

In the video shown, we saw that the effect of this was that the LED got brighter and dimmer as the resistance varied.

In the last video the LED was connected to the potentiometer using a resistor. What will happen if we replace the resistor with a basic cable?

1. It will get brighter
2. It will get dimmer
3. Nothing at all

Before we go on, let's talk about resistors.

Resistance is calculated in Ohms (Ω)

We can see that each resistor has 4 lines painted on it. These lines are simply telling us their resistance.

• 1st line - 1st digit of our amount
• 2nd line - 2nd digit of our amount
• 3rd line - the multiplier for our first two digits
• 4th line - the tolerence of the resistor i.e. its percentage error

Let's try one out!

What is the resistance of this Diode?

• Answer:
  470Ω ±5%

True of False:
Every component in a circuit has some resistance.

1. True
2. False

00:09

Connected to the same potentiometer we have 3 LEDs. 1 LED will be by itself and the other 2 will be connected together. Which LED/s will be brighter?

1. The one that's alone
2. The two that are together
3. All will be the same

So why did that happen?

Circuits can be connected in 2 ways:

- Parallel: the 2 LEDs and the 1 alone were connected in parallel, they are uneffected by each other

-Series: the 2 LEDs are connected to each other in series, the means their combined resistance has an effect on the shared current

What else do you think we could do with circuits?

Let's have some fun with colour

Remember this weird looking LED from earlier?

This is an RGB LED.

• R - Red
• G - Green
• B - Blue

Let's see what happens when we use it in a circuit!

00:09

The RGB LED contains all three colours together. What will happen if we don't add resistors?

1. It will be fine
2. It will burn the RGB LED
3. It will only show red
4. It will show all the colours

01:25

What colour will the LED be when we press the red and blue buttons?

01:29

What about blue and green?

01:33

And red and green?

01:37

And lastly, what happens when we press all three?

The Buzzer

Our last component is going to be the buzzer!

This component unlike all the other components we saw, emits sound rather than light.

WARNING: It's really annoying!

00:20

This looks familiar. What was this called?

1. Diode
2. Voltmeter
3. Capacitor
4. Potentiometer

00:39

What will the variable resistor (potentiometer) be affecting?

What did you find most interesting/fun about the circuit basics?

Thank You!

It's pretty easy so go ahead and have fun with your breadboard :) 

Bye!