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3.1 Voltage (V)
Voltage is the difference in electrical energy between two parts of a circuit.
A voltmeter can be used to measured volts and its symbol is V.
Voltage is also known as electric potential difference, electric pressure or electric tension.
3.2 Current (I)
Current is the flow of electric charge through a circuit.
Current can be measured with an ammeter in amperes. The symbol for current is (I) and (A) is the amperes symbol.
3.3 Resistance (Ω)
Electrical resistance measures difficulty that an electrical component offers to the flow of electricity through it.
Resistance is measured in ohms (Ω) by an ohmmeter.
3.4 Measuring electrical magnitudes.
We have seen that that every magnitude requires its own meter, but you can measure all this magnitudes with a multimeter or multitester, an electronic device that combines a voltmeter, ammeter and ohmmeter among others.
How can we use it?
Take a look at the following link and investigate:
Now in pairs measure the battery voltage, resistance of the light bulb and the amperes of the light bulb circuit and jot down the magnitudes to discuss with your classmates.
There are two main types of different basic circuits. Watch the following video and try to understand their differences.
Let's see if you know the main differences by fill-in the gaps:
a) ____________________ will only flow on a closed circuit.
b) Notice that the _____________ flow through the wire and each of the bulbs before they return to the ________________.
c) If one of the _________ breaks, a gap occurs in the circuit and all the lights go _______.
d) When lights are lined up one after the other on a circuit like these lights are, it is called a ________________ circuit.
e) In a ______________ circuit the wires that are connected to ___________ run parallel to each other rather than having all the bulbs in a row.
f) This means that one light can burn out or be ___________________, and the other lights on the circuit will stay__________________.
4.1 Total resistance calculation.
In order to solve series and parallel circuits, we must know the total resistance of all their elements.
Calculating this total resistance will not too much time, especially in series circuits.
Series circuits: Rt = R1+R2+R3+ ... +Rn
Paralell circuits: 1/Rt = 1/R1 + 1/R2 + 1/R3 + ... + 1/Rn
We can start introducing Ohm's law by watching the following video and answering the following questions:
Who was Georg Ohm?
When did he publish Ohm's law?
What happened to him after that?
How long did we wit for recognition?
Did he make only electric researches?
5.1 Ohm's law statement
V=I*R
V = measured in volts units
I = measured in amperes units
R = measured in ohms units
Ohm's law, states that the current through a conductor between two points is directly proportional to the voltage across the two points.
More specifically, Ohm's law states that the R in this relation is constant, independent of the current.
Before starting with quizzes and exercises, take a look at this video and review some of the content that we are supposed to know.
This video will review circuits, Ohm's law and total resisitance calculating. Don't miss it!
In the link buttons of this unit you will find some quizzes about circuits and Ohm's law.
Short url: https://clilstore.eu/cs/5468
