Physics Problem -- Electricity and Circuits?
I've got a study problem that I don't know how to work out. I don't need the actual solution, just the method.
It's an electrical circuit, 20V supply, two resistors in parallel of 12 and 4 ohms and then a 7 ohm resistor further down the circuit. The question is: calculate the current through the 12 ohm resistor.
I've looked everywhere in my notes and I cannot figure out how to answer this question.
Please help!
Answers:
This will take a few steps.
Step 1. Find the equivalent resisitance of the 12 and 4 ohm
resitor. Reqv = R1(R2)/(R1+R2) = 12x4/16 = 3
So you have a 3 ohm and 7 ohm resistor in series. This gives
a circuit current of V/Rtotal = 20/10 = 2amp
Now the voltage drop across the 7ohm resitor is 7x2 = 14 volts
and the voltage drop across the equival 3ohm resitor is 3x2 = 6 volts.
This 6 volts is across the 12 ohm resitor, so the current
througth it is V/R = 6/12 = .5
Use the Ohms law equation its easy. V=IR I - assumes you did take notes on how to work out the resistance in a parallel circuit!
Work out the resistance of the two resistors in parallel. You can then work out the total resistance and the total current. Now work out how the current is divided between the two resistors in parallel. Just remember that Ohm's Law applies to every part of the circuit.
1) Calculate the total resistance (equivilant) in the circuit.
a) 1(1/12 + 1/4) + 7 = 10 ohms
2) current drawn from the source = 20/10
3) the 2 amps of current is split inversely berween 12 ohm and 4 ohms.
4) i.e. in the ratio 1: 3
5) so the current in 12 ohm res. is 0.5 amps
do u mean to say there r 3 resistors in parallal?. I''m assuming ur 7ohm resistor is also in parallel.
All u hav to know is voltage will be the same across all parallel connections.. only current gets divided. so i=v/r = 20/12
First calculate resistance in Parallel 12 & 4 =3
because the 12 & 3 ohm are in parallel you must calculate the VD across the sum of the 2 resistors i.e. 3
look at the website below for help. Not going to give you all the answers you have to learn
Good Luck
The resistance of the two in parallel is 3 ohms plus the 7 in series gives you a total of 10. With a 20 volt supply you get 2 amps flowing out of the battery. To calculate the proportion of the 2 amps which flows through the two resistors in parallel work it out by proportion. I'm not doing all your homework for you.
Calculate the effective resistence over the resistors in parallel:
1/Rt = 1/R1 + 1/R2 = 1/12 + 1/4 = 4/12 = 1/3
So the voltage over the parallel resistors is the equivalent of the voltage over a 3ohm resistor.
V = IR, so I = V/R = 20/(3+7) = 2.
So I'd say 0.5 A goes through the 12 ohm as it is 3 times bigger than the 4ohm resistor.
12 and 4 in parallel is 3ohms.
This in series with 7ohm.
Total circuit resistance 10 ohm.Voltage is 20.
Volt drop per ohm is 2volts.
Therefore 6volts across parallel leg.
So 6volts across 12 gives 6/12=1/2amperes or 500 Milliamps
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It's an electrical circuit, 20V supply, two resistors in parallel of 12 and 4 ohms and then a 7 ohm resistor further down the circuit. The question is: calculate the current through the 12 ohm resistor.
I've looked everywhere in my notes and I cannot figure out how to answer this question.
Please help!
Answers:
This will take a few steps.
Step 1. Find the equivalent resisitance of the 12 and 4 ohm
resitor. Reqv = R1(R2)/(R1+R2) = 12x4/16 = 3
So you have a 3 ohm and 7 ohm resistor in series. This gives
a circuit current of V/Rtotal = 20/10 = 2amp
Now the voltage drop across the 7ohm resitor is 7x2 = 14 volts
and the voltage drop across the equival 3ohm resitor is 3x2 = 6 volts.
This 6 volts is across the 12 ohm resitor, so the current
througth it is V/R = 6/12 = .5
Use the Ohms law equation its easy. V=IR I - assumes you did take notes on how to work out the resistance in a parallel circuit!
Work out the resistance of the two resistors in parallel. You can then work out the total resistance and the total current. Now work out how the current is divided between the two resistors in parallel. Just remember that Ohm's Law applies to every part of the circuit.
1) Calculate the total resistance (equivilant) in the circuit.
a) 1(1/12 + 1/4) + 7 = 10 ohms
2) current drawn from the source = 20/10
3) the 2 amps of current is split inversely berween 12 ohm and 4 ohms.
4) i.e. in the ratio 1: 3
5) so the current in 12 ohm res. is 0.5 amps
do u mean to say there r 3 resistors in parallal?. I''m assuming ur 7ohm resistor is also in parallel.
All u hav to know is voltage will be the same across all parallel connections.. only current gets divided. so i=v/r = 20/12
First calculate resistance in Parallel 12 & 4 =3
because the 12 & 3 ohm are in parallel you must calculate the VD across the sum of the 2 resistors i.e. 3
look at the website below for help. Not going to give you all the answers you have to learn
Good Luck
The resistance of the two in parallel is 3 ohms plus the 7 in series gives you a total of 10. With a 20 volt supply you get 2 amps flowing out of the battery. To calculate the proportion of the 2 amps which flows through the two resistors in parallel work it out by proportion. I'm not doing all your homework for you.
Calculate the effective resistence over the resistors in parallel:
1/Rt = 1/R1 + 1/R2 = 1/12 + 1/4 = 4/12 = 1/3
So the voltage over the parallel resistors is the equivalent of the voltage over a 3ohm resistor.
V = IR, so I = V/R = 20/(3+7) = 2.
So I'd say 0.5 A goes through the 12 ohm as it is 3 times bigger than the 4ohm resistor.
12 and 4 in parallel is 3ohms.
This in series with 7ohm.
Total circuit resistance 10 ohm.Voltage is 20.
Volt drop per ohm is 2volts.
Therefore 6volts across parallel leg.
So 6volts across 12 gives 6/12=1/2amperes or 500 Milliamps
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