Lesson: Circuits Contributed by: Integrated Teaching and Learning Program, College of Engineering,...
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Transcript of Lesson: Circuits Contributed by: Integrated Teaching and Learning Program, College of Engineering,...
Lesson: Circuits Contributed by: Integrated Teaching
and Learning Program, College of Engineering, University of Colorado at
Boulder
Keywords:
capacitor, circuit, coulomb, current, electrical, electricity, electronic, energy, inductor, Ohm's law, power, resistance, resistor, volt, voltage
Learning Objectives
Define electric current and voltage.
Explain the relationship between voltage, current and resistance (Ohm's law).
List several different circuit components.
Thinking
Do you know why a cell phone must have a battery or why a computer must be plugged in to work?
(Answer: Those devices need electricity to work.)
Open vs Closed Circuits
Did you know that a battery or the power coming from the outlet in the wall is part of an electrical circuit?
When a battery is placed in the cell phone or when a computer is plugged in, the circuit in the device is completed or "closed," allowing electric current to flow.
Types of Engineers
Electrical Engineers: are most commonly associated with the development of circuits, but they are not the only engineers who work with and know about circuits. Most engineers must understand electricity and the physics behind circuits so they can design any devices that use electricity.
Mechanical engineers, for example, use circuits when designing motors.
Aerospace engineers use circuits when designing controls for spacecraft.
Resistor
resistors (any two terminal objects that provide a voltage drop in order to oppose the flow of current through it)
Integrated Circuit
An integrated circuit is one that has been designed to perform a given task and is often made up of several other components such as resistors, capacitors, inductors and transistors.
Unit of Current is Ampere (A) /Amp
Currents found in household devices are generally around 1 amp. However in electronic devices such as stereos and computers, the current is often on the scale of milliamps (1mA = 10-3A) or microamps (1μA = 10-6A).
Two types: Alternating & Direct
Alternating current comes out of your typical wall sockets in homes, schools and businesses. It is called "alternating" because the direction of the current is constantly changing.
Alternating Current
In the US, the alternating current from wall sockets is at 60 Hz (Hertz). This means that the current is changing directions 60 times every second.
60 Hz (Hertz) = 60 times every second
Direct Current
Direct current is the current produced by batteries. It always travels in one direction. Current is important because the moving charges carry energy and have a potential to do work.
Voltage
Voltage = Electric Potential = The pressure that forces electricity through wire.
The unit for voltage is the volt (V).
AA, AAA, C, and D batteries are all 1.5v
Car batteries are 12v
Lawn mower batteries are 6v
Motorcycle batteries are 6v or 12v
Smoke detectors use 9v batteries
Ohm’s Law V=IxR
Ohm's law states that the voltage across a resistor is proportional to the current flowing through the resistor.
In equation form, it looks like this:
V = I x R
V = Voltage (volts) V
I – Current (amps) A
R = Resistance (Ohms) Ω
10V = 2A x 5 Ω