CALCULATING ELECTRICITY TODAY WE ARE GOING TO LOOK AT CURRENT VOLTAGE RESISTANCE.
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Transcript of CALCULATING ELECTRICITY TODAY WE ARE GOING TO LOOK AT CURRENT VOLTAGE RESISTANCE.
CALCULATING ELECTRICITYTODAY WE ARE GOING TO LOOK AT
•CURRENT•VOLTAGE•RESISTANCE
Ok lets begin
Look at this video below lets see what we learn• http://www.youtube.com/watch?v=KvVTh3ak
5dQ&feature=related
“Answer me this”
• From the video look at the following questions– Can you define current– Can you define voltage– Can you define resistance– What are the units of measurement of each
Current
• Current is the flowing of negative charges from one point to the other
• The symbol for current is I• The unit of measurement of current is amperes(amps)• Current is measured using an ammeter
Voltage
• The force or energy involved in pushing the charges around is referred to as E.M.F.
• Across electrical components there are energy differences called Potential difference or VOLTAGE
• The symbol for Voltage is V• The unit of measurement is Volts(V)• Voltage is measured using a voltmeter
Resistance
• Resistance is the opposing of the flowing of current
• The symbol of resistance is R• The unit of measurement is Ohms(Ω)• Resistance can be measured using a
multimeter however R can be calculated
The Relationship between I, V & R
• Well some dude came up with this law that makes us calculate R
• Ohms law- the current flowing in a conductor maintained at a constant temperature is proportional to the potential difference(voltage) between its ends
• Well all that means is simply V= IR
“The triangle to remember”
Let’s practice
• Calculate the current flowing through a circuit is the voltage is 9 V and the resistance is 3 ohms.
Ok Good effort , here’s my answer
• What do I want to find– Current-I
• What do I have – V=9V & R=3Ω
• What do I know– V=IR
• Then I solve• 9=I * 3• I= 9/3• I= 3 A
Let’s practice
• Calculate the voltage flowing through a bulb if the current passing through it is 15 A and the resistance of the bulb is 3Ω.
Ok Good effort , here’s my answer
• What do I want to find– Voltage-V
• What do I have – I=15A & R=3Ω
• What do I know– V=IR
• Then I solve• V=15*3• V=45V
Let’s practice
• Calculate the resistance in a circuit if the voltage of the power supply is 4.5 V and the current flowing through is 1A
Ok Good effort , here’s my answer
• What do I want to find– Resistance-R
• What do I have – I=1A & V=4.5V
• What do I know– V=IR
• Then I solve• 4.5=1*R• R=4.5/1• R=4.5Ω
Why do we need this
• Understanding values helps know how much electricity is required to make something work
• It helps us to determine safety since can calculate the amount of electricity flowing through an electrical component so this would not happen to us
• http://www.youtube.com/watch?v=M4qzMbpy0ks
Current in parallel and series
• Series – Current flowing through components in series is
the same through each component• Voltage – Current flowing through a parallel circuit splits up
and recombine at the connecting points
Voltage in series and parallel
• Series – The voltage across components in series is
different because “potential difference” charges across each component
• Parallel– The voltage is the same across things in parallel
JUST FOR YOUR REVIEW
• http://www.youtube.com/watch?v=bnzmVAa46xg&feature=fvwrel
• http://www.youtube.com/watch?v=LOEiA9yAh6E&feature=related