power factor

[PoorFish]

what is the power factor of a circuit with a 4 ohms resistor and a 10mH inductor??

any ideas anyone

I have tried the R/Z formula but it doesnt seem to work

regards P

 

[bobby]

Hey I posted the exact same question as you a few days ago with the same title here is your awnser credits go to wayne

Find Z first

Z = √R

 

[PoorFish]

cheers Bobby

getting late and been at this too long tonight

i must have looked at that post a number of times already

thanks for reply will look at it closer tomorrow

PatGuiness Drink

 

[a1pacino]

for this question do you not have to work out the xl inductive reactance? -

(xl = 2 x crbvcurbvubruvbruvb x f x l) xl = 2x3.14x50x(10x10-3=0.01) to work out impedance?

I get

R = 4ohms

Z = 4ohms

so pf = R/Z = 4/4 = 1

is that correct?

 

[septiclecky]

for this question do you not have to work out the xl inductive reactance? - 2x3.14x50x(10x10-3=0.01) to work out impedance?

I get Z = 4ohms so pf = R/Z = 4/4 = 1

????

 

[msb2003]

I would agree you need to work out the imductive reactance XL.

With no frequency given you can only assume 5o Hz so

XL = 2 x 3.14 x 50 x (10 x 10-3)

XL = 3.14 ohms

Impeadance (Z) is the Square Root of (R squared + XL squared)

Z = Root ((4 x 4) + (3.14 x 3.14))

Z = 5.08

pf = R / Z

pf = 0.78

All on the assumption of 50Hz supply!!!!!!!

 

[a1pacino]

that makes more sense, cheers!

 

[Andy™]

maybe im missing something but

XL = 2 x 3.14 x 50 x (10 x 10-3)

XL = 3.14 ohms

is 31.4 ohms

 

[msb2003]

maybe im missing something butXL = 2 x 3.14 x 50 x (10 x 10-3)

XL = 3.14 ohms

is 31.4 ohms

Don't put in the 10 in the 10-3, that might be where you're going wrong.

10 x 10-3 = 0.01 10 to the power minus 3 (or 10 / 1000)

so try 2 x 3.14 x 50 x 0.01

that comes out as 3.14 ohms

 

[Andy™]

Don't put in the 10 in the 10-3, that might be where you're going wrong.10 x 10-3 = 0.01 10 to the power minus 3 (or 10 / 1000)

so try 2 x 3.14 x 50 x 0.01

that comes out as 3.14 ohms

10x10-

 

[Apache]

10x10-

 

[Andy™]

It's not Andy - it's 0.01 :|

well the calculator is wrong!

 

[Apache]

well the calculator is wrong!

ok!

10x10-

 

[Apache]

(i know its a bad pic, had to cover the flash or it just blinded everything)

I prefer a Caseo over the Sharpe - especially if it can't calculate properly............

 

[Apache]

ooh delete your post that I have quoted........

 

[Andy™]

ok!10x10-

 

[Andy™]

ooh delete your post that I have quoted........

it can calculate properly... just depends how you enter it into the calc....

 

[Andy™]

ooh delete your post that I have quoted........

no problem...

 

[Apache]

now if you type 10x10-

 

[Andy™]

i left school 7 years ago (im starting to feel old!)... and you expect me to remember maths from that long ago?!