ELECTRICAL CIRCUIT-Noughts&Crosses

• Science
• Middelbare school
• vwo
• Leerjaar 2

Electric current is the flow of electrons through a complete circuit of conductors. It is used to power everything from our lights to our trains.

What Are Conductors?

• An electrical conductor is defined as materials that allow electricity to flow through them easily.
•  This property of conductors that allow them to conduct electricity is known as conductivity.
  
• The flow of electrons in a conductor is known as the electric current. 
• The force required to make that current flow through the conductor is known as voltage.

Examples of Conductors

Graphite, the human body, and the earth are good conductors of electricity. Some of the common conductor examples include metals such as copper, gold, iron etc.

Electricity is a flow of charge 

Electricity is a flow of charge 

Electricity is a flow of charge 

Properties of Electric charge

Charge can neither be created nor be annihilated.

Opposite charges attract each other, Like charges repel each other.

Conventional current and electron flow

• Electron current flows from the negative terminal to the positive terminal of the battery. 
• The conventional current flows from the positive terminal of the battery to the negative terminal.

Electric Charge

• The thing with electrons is: There are SO many!

• We don't measure charge in the number of electrons, but in batches.

• One such batch is one coulomb.

What is current 

Electrical current is a measure of the amount of electrical charge (electrons) transferred per unit of time. It represents the flow of electrons through a conductive material, such as a metal wire

What is current?

You already know:

• Electricity is a flow of charge.

This can be

Quantified

First, pause the video and try to answer it for yourself. After that continue playing the video.

What is current?

You already know:

• Electricity is a flow of charge.

This can be

Quantified

The amount of coulomb flowing through an electric circuit per second — Coulomb/second

First, pause the video and try to answer it for yourself. After that continue playing the video.

What is current?

• Symbol: I
  
• Unit: Ampere (A)
• Formula:                           Current = Charge / time

Charge — Coulombs (C)

time — seconds (s)

I=​t​​Q​​

The amount of coulomb flowing through an electric circuit per second —  Coulomb/second

First, pause the video and try to answer it for yourself. After that continue playing the video.

Resistors

We use resistors to control the flow of current from a voltage source, like a battery.

They resist the flow of charge, they are poor conductors.

The value of resistor is measured in ohms and represented by the Greek letter capital omega.

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%

(LED)

The LED symbol is the standard symbol for a diode, with the addition of two small arrows denoting the emission of light.

LED

A light-emitting diode (LED) is a semiconductor device that emits light when an electric current flows through it. When current passes through an LED, the electrons recombine with holes emitting light in the process. LEDs allow the current to flow in the forward direction and blocks the current in the reverse direction.

The figure below shows a simple LED circuit.

The circuit consists of an LED, a voltage supply and a resistor to regulate the current and voltage.

 Additional Information..!

How does an LED work?

When the diode is forward biased, the minority electrons are sent from p → n while the minority holes are sent from n → p. At the junction boundary, the concentration of minority carriers increases. The excess minority carriers at the junction recombine with the majority charges carriers.

             Additional Information..!

In LEDs, the energy is released in the form of photons on recombination.  We call this phenomenon electroluminescence. Electroluminescence is an optical phenomenon, and electrical phenomenon where a material emits light in response to an electric current passed through it. As the forward voltage increases, the intensity of the light increases and reaches a maximum.

Additional Information..!

What determines the colour of an LED?

The colour of an LED is determined by the material used in the semiconducting element. The two primary materials used in LEDs are aluminium gallium indium phosphide alloys and indium gallium nitride alloys. Aluminium alloys are used to obtain red, orange and yellow light, and indium alloys are used to get green, blue and white light. Slight changes in the composition of these alloys change the colour of the emitted light.

Uses of LED

LEDs find applications in various fields, including optical communication, alarm and security systems, remote-controlled operations, robotics, etc. 

It finds usage in many areas because of its long-lasting capability, low power requirements, swift response time, and fast switching capabilities. 

 A few standards LED uses:

Used for TV back-lighting

Used in displays

Used in Automotives

LEDs used in the dimming of lights

Advantages of LEDs over Incandescent Power Lamps

Some advantages of LEDs over Incandescent Power Lamps are:

LEDs consume less power, and they require low operational voltage.

No warm-up time is needed for LEDs.

The emitted light is monochromatic.

They exhibit long life and ruggedness.

Advantages of LEDs over Incandescent Power Lamps

LEDs consume less power, and they require low operational voltage.

No warm-up time is needed for LEDs.

The emitted light is monochromatic.

They exhibit long life and ruggedness.

What is the unit for electrical current?

1. V for Voltage
2. A for amps
3. W for Watts
4. v for Speed