Electronic Principles Home Work

[Andrew Younger]

Hi I am struggling with a question at the moment and wonder if someone can help me get my head around it.

Calculate C for a mica capacitor with:
- Relative permittivity: 8
- thickness of: 0.02cm
- Plates of 6cm2

I have got for the equation:
C= A/d x ER E0

So:
C = 6 x 10*4 / 0.02 x 10*-2 x 8 x 8.85 x 10*-12 = The answer I am getting is 2.124 x 10*-14

Where am I going wrong?? Thanks for any help

 

[Arouse1973]

Hi Andrew
What is the 6*10^4? Do you think that should be -4?
Thanks
Adam

 

[duke37]

It would be better to use SI units. Why make things complcated with sub units?
It would be better to use brackets to define your equation properly or rearrange to not need them.

Wikipedia gives E0 as 8.85E-12 Farads/m
Area 6cm2 = 6E-4m^2 Check this, the area could be 6cm by 6cm i.e. 36cm^2
Thickness = 0.02cm = 2E-4 m
C = A* Er*E0/d =212pF

Please check, my abacus and its driver are quite old.

 

[Arouse1973]

I did think that about the units but I guess they want them to spot that and try and work it out. Your wooden beads are working correctly Trevor.
Adam