Intro to Electrical Engineering

Laws:

Ohms Law:

• Ohms law states that voltage is equal to current times resistance.
  • V = Power/Voltage
  • R = Resistance
  • I = Current
    • V = IR
    • R = V/I
    • I = V/I

Kirchoff's Law:

• Voltage
  • The sum of all of the volts in a series is equal to the totals volts.
    • V_T= V₁ + V₂ + V₃
  • The amount of volts in parallel is equal in all locations.
    • V₁ = V₂ = V₃ = V₄

• Current
  • The amount of current is equal in all places in series.
    • I₁ = I₂ = I₃ = I₄
  • The sum of all the current in parallel is equal to the total current.
    • I₁ = I₂ = I₃ = I₄

• Resistance
  • The sum of all of the resistance in series is equal to the total resistance.
    • R_T= R₁ + R₂ + R₃
  • The total amount of resistance is equal to the sum of the resistance over under one.
    • 1/R_T = 1/R₁ + 1/R2 + 1/R₃

Homemade Battery:

• In class, we made homemade batteries by using lemon juice, copper pennies, and zinc screws. We had to make sure that the zinc and the penny were not touching each other in order for the project to work. We were able to produce enough voltage to light up a LED.
• The reason our battery worked was because when the zinc reacts with the acid (from the lemon juice) it creates a surplus of electrons which then need somewhere to go and they go through the wire to the copper penny creating a chemical reaction which leads to power. The electrons moving creates the power.
• We made a primary battery which means that the battery worked as soon as it was connected.

• Our lemon battery reaction caused the LED to light up.

• Our battery didn't originally work because the screws and penny were touching.

• Our team worked on the battery.

• Once we fixed the problem with the touching screws and zinc then we got about 2 volts from our battery.

Resistor:

• A resistor is something that controls the flow of current, so if you have more resistance not as much voltage can pass through.

Diode:

• A diode is something that allows current to flow in only one direction. A light emitting diode is often referred to as a LED.

LED:

• A LED is a light emitting diode. This means that when a LED receives electricity it produces light.

Switch:

• A switch controls the flow of current meaning that when the switch is in an on position, the current will be allowed to complete the circuit, but the switch is in an off position then the circuit will not be complete and therefore will not function.

Momentary Switch:

• A momentary switch only changes when a button is pushed. If the switch is normally closed (meaning the circuit is working) then when the button is pressed the circuit become incomplete. If the switch is normally open (meaning the circuit is not completed) than if it is pressed, then the circuit will be completed and it will be able to accomplish what is supposed to do.
• Let's use an example: Computer keyboard: The key are all momentary switches because when they are not being pressed they do not complete the circuit and nothing happens, but if you press a key then the circuit is complete and the key is written on your computer screen.

Relay:

• A relay is a type of switch that is turned on when some current is run through it. It has a magnet inside of it that helps change the switches. Relays can be very helpful because they can regulate large current.

• In class we made two relay circuits on had the button on the entry side that controlled wether or not the second light turned on and the second one changed were the buttons power was coming from:

Transistor:

• A transistor is a component that can regulate the amount of current flowing through a circuit. It can act as a switch to allow changes in current. It can act as a switch or an amplifier. It can make the current larger or it can direct the flow of current through it.

Capacitor:

• A capacitor is something that stores an electrical charge. It is sort of similar to a battery because of the fact they both store charges, but a battery can produce electrons and a capacitor can only store them.

Schematics: