How to Find The Potential Differences and Values Of I1, I2 and I3?
Hi all am stuck on this question? cant figure out the Potential Differences, and i1 , i2 and i3.
The image is below
http://s1331.photobucket.com/user/spearemail1993/media/Picture1_zps47a5528b.jpg.html
Cheers
The image is below
http://s1331.photobucket.com/user/spearemail1993/media/Picture1_zps47a5528b.jpg.html
Cheers
Original post by gogetter1989
Hi all am stuck on this question? cant figure out the Potential Differences, and i1 , i2 and i3.
The image is below
http://s1331.photobucket.com/user/spearemail1993/media/Picture1_zps47a5528b.jpg.html
Cheers
The image is below
http://s1331.photobucket.com/user/spearemail1993/media/Picture1_zps47a5528b.jpg.html
Cheers
You will need to know: how to work out series and parallel resistances.
Ohms law (V/I = R). Basic Kirchoffs laws: (Volts dropped around a circuit sum to the supply, branch currents sum at a node).
i) Find the total current. Do this by first finding an equivalent value for the parallel resistance and sum that with the series resistance to get the total circuit resistance. Use Ohms law to work out the total current.
ii) Next use Ohms law again with V as the subject and by applying the total current to each of the series resistors and aso the equivalent parallel resistance. Ths will give you the voltage dropped across each series resistor.
iii) Once you have the voltages, use the pd across the equivalent series resistance and Ohms law finaly (with I as the subject), applied to each parallel resistor. This gives you the current trog each branch of the parallel resistors.
done the voltages so:
v1= 100ma (0.1a) 0.1 *1k ohms ( 1000 ohms) = 100v
v2= 100v
v3= 50v
a quick question , Usually i thought that 1k ohms would mean 1 * 10 to the power of 3 , does this not apply in this type of situation or if not when does it?
v1= 100ma (0.1a) 0.1 *1k ohms ( 1000 ohms) = 100v
v2= 100v
v3= 50v
a quick question , Usually i thought that 1k ohms would mean 1 * 10 to the power of 3 , does this not apply in this type of situation or if not when does it?
Original post by gogetter1989
done the voltages so:
v1= 100ma (0.1a) 0.1 *1k ohms ( 1000 ohms) = 100v
v2= 100v
v3= 50v
a quick question , Usually i thought that 1k ohms would mean 1 * 10 to the power of 3 , does this not apply in this type of situation or if not when does it?
v1= 100ma (0.1a) 0.1 *1k ohms ( 1000 ohms) = 100v
v2= 100v
v3= 50v
a quick question , Usually i thought that 1k ohms would mean 1 * 10 to the power of 3 , does this not apply in this type of situation or if not when does it?
Voltages all correct.
1x103 = 1 x (10 x 10 x 10) = 1 x 1000 = 1000.
Why do you think it does not apply in ANY situation?
When calculating the voltages dropped around a series circuit between two points using KVL, it's the ratio of the resistances that are important.
So for instance 90V across 2 resistors of 475 ohms and 950 ohms in series are in the ratio 1:2. The Pd across each wil therefore be 30V and 60V respectively. i.e. the pd's are in the same ratio (30:60 = 1:2) as that of the resistances.
Try it with 90V and 22000 ohms and 44000 ohms. the pd's will still be 30 and 60V respectively.Notice, current did not feature in the voltage calcuation because we used ratios instead.
The answer using ohms law is the same:
V=90V
Rtotal = 475 + 950 = 1425 ohms
Itotal = V/R = 90/1425 = ohms
Then pd across 475 ohm resistor is IxR = 0.0632 x 475 = 30V
pd across 950 ohm resistor is IxR = 0.0632 x 950 =60V
Practice using ohms law first until you understand fully and are competent/comfortable and only then try with ratio's.
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