# Can somebody help/check do writeWatch

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#1
Find voltage drop across resistor and capacitor in RLC series circuit
it has reisistor (7omh), capacitor (58x10^-6F), Voltage supply 100v 150 Hz

I = V/R
100/7 = 14.2A
series so current will be same for capacitor.

Voltage drop over Resistor
I x R = V
7 x 14.2 = 99.4v

Inductance reactance
Xc = 1/2piFc
Xc = 2Pi (58x10^-6) x 150
Xc = 18.4

Vc = I x Xc
Vc = 14.2 x 18.4
Vc = 258.4

sorry kind of stuck

do i use I/V = Z, to find XL
Last edited by mlm1234; 2 weeks ago
0
2 weeks ago
#2
(Original post by mlm1234)
Find voltage drop across resistor and capacitor in RLC series circuit
it has reisistor (7omh), capacitor (58x10^-6F), Voltage supply 100v 150 Hz

I = V/R
100/7 = 14.2A
series so current will be same for capacitor.

Voltage drop over Resistor
I x R = V
7 x 14.2 = 99.4v

Inductance reactance
Xc = 1/2piFc
Xc = 2Pi (58x10^-6) x 150
Xc = 18.4

Vc = I x Xc
Vc = 14.2 x 18.4
Vc = 258.4

sorry kind of stuck

do i use I/V = Z, to find XL
https://www.electronics-tutorials.ws...s-circuit.html
Is pretty decent explanation, you must have something similar in your notes?

You don't mention what the inductor is in the question etc.
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#3
(Original post by mqb2766)
https://www.electronics-tutorials.ws...s-circuit.html
Is pretty decent explanation, you must have something similar in your notes?

You don't mention what the inductor is in the question etc.
Thats the all the info i got
we did it with inductor (henerys) in class but not when there isnt a inductor
so got me stuck
0
2 weeks ago
#4
(Original post by mlm1234)
Thats the all the info i got
we did it with inductor (henerys) in class but not when there isnt a inductor
so got me stuck
You said its an RLC circuit though?
0
#5
(Original post by mqb2766)
You said its an RLC circuit though?
we where doing rlc series circuits. but thats the question they gave us so dont know.
0
2 weeks ago
#6
(Original post by mlm1234)
we where doing rlc series circuits. but thats the question they gave us so dont know.
If there is an inductor, you need to know L?

If its RC
https://www.electronics-tutorials.ws...pacitance.html
Last edited by mqb2766; 2 weeks ago
0
#7
(Original post by mlm1234)
we where doing rlc series circuits. but thats the question they gave us so dont know.
(Original post by mqb2766)
If there is an inductor, you need to know L?

If its RC
https://www.electronics-tutorials.ws...pacitance.html
The circuit for example RC looks like it matchs the question because no inductor.
Tutor just gave use z = root r^2 + (Xc - Xl^2) and was just talking about RLC circuits an dpower factors so prob got confused with that
cheers.
0
2 weeks ago
#8
(Original post by mlm1234)
The circuit for example RC looks like it matchs the question because no inductor.
Tutor just gave use z = root r^2 + (Xc - Xl^2) and was just talking about RLC circuits an dpower factors so prob got confused with that
cheers.
Id agree its probably just an RC question. See how far you get with that info. The questions are not too hard once you get used to them.
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#9
(Original post by mqb2766)
Id agree its probably just an RC question. See how far you get with that info. The questions are not too hard once you get used to them.
Inductance reactance
Xc = 1/2piFc
Xc = 2Pi (58x10^-6) x 150
Xc = 18.4

Z = root(R^2 + Xc^2)
Z = root(7^2 + 18.2^2)
Z = 19.3

Vc = 100 (supply voltage)
I = Vc/Z
I = 100/19.3
I = 5.1

Tan^-1 (Xc/R) = phase angel
Tan^-1 (18.4/7) = 69.1

voltage drop
Vr = 5.1 x 18.4 = 93.8
Vc = 5.1 x 7 = 35.7
Vsupply = root(93.8^2 + 35.7^2) =100

Power Factor
CosO (R/Z)
Cos 7/19.3 = 68.7

is that right not sure on the power factor tho
do i draw a phasor digram
0
2 weeks ago
#10
(Original post by mlm1234)
Inductance reactance
Xc = 1/2piFc
Xc = 2Pi (58x10^-6) x 150
Xc = 18.4

Z = root(R^2 + Xc^2)
Z = root(7^2 + 18.2^2)
Z = 19.3

Vc = 100 (supply voltage)
I = Vc/Z
I = 100/19.3
I = 5.1

Tan^-1 (Xc/R) = phase angel
Tan^-1 (18.4/7) = 69.1

voltage drop
Vr = 5.1 x 18.4 = 93.8
Vc = 5.1 x 7 = 35.7
Vsupply = root(93.8^2 + 35.7^2) =100

Power Factor
CosO (R/Z)
Cos 7/19.3 = 68.7

is that right not sure on the power factor tho
do i draw a phasor digram
Im getting roughly the same but the odd diff in 1dp, possibly bevause of pi? You have X = both 19.2 and 19.4, I got 19.3 and the follow on ...

Also is the voltage drop the right way round?
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#11
(Original post by mqb2766)
Im getting roughly the same but the odd diff in 1dp, possibly bevause of pi? You have X = both 19.2 and 19.4, I got 19.3 and the follow on ...

Also is the voltage drop the right way round?
how do u mean right way round?
and is the power factor ok
wasnt 100% on how to calculate power factor
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2 weeks ago
#12
(Original post by mlm1234)
how do u mean right way round?
and is the power factor ok
wasnt 100% on how to calculate power factor
Vr = I*Xc ?

Edit: for reactive power factor you should have something like V*I*sin(phase)?
Not sure what you're doing?
Last edited by mqb2766; 2 weeks ago
0
#13
(Original post by mqb2766)
Vr = I*Xc ?

Also ypur phase should be negative? Is it lagging or leading?

Edit: for reactive power factor you should have something like V*I*sin(phase)?
Not sure what you're doing?
voltage drop
Vc = 5.1 x 18.4 = 93.8
Vr = 5.1 x 7 = 35.7
Vsupply = root(93.8^2 + 35.7^2) =100

how do u woek out Power Factor
0
2 weeks ago
#14
(Original post by mlm1234)
voltage drop
Vc = 5.1 x 18.4 = 93.8
Vr = 5.1 x 7 = 35.7
Vsupply = root(93.8^2 + 35.7^2) =100

how do u woek out Power Factor
Given in previous post?
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#15
(Original post by mqb2766)
Given in previous post?
sorry is that phase angle in the equation
was looking fir voltage drop then power factor
0
2 weeks ago
#16
0
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