IET
 Topic Title: capacitors,dielectrics.......help me out Topic Summary: question on dielectric Created On: 16 November 2010 09:00 PM Status: Read Only Linear : Threading : Single : Branch
Search Topic
Topic Tools
 View similar topics Print this topic.
 16 November 2010 09:00 PM bheka Posts: 2 Joined: 16 November 2010 a capacitor is to be constructed so that its capacitance is 0.2micro farad and to take a p.d of 1.25kV across its terminals.The dilelectric is to be mica which after allowing a safety factor of 2 has a dielectric strenght of 50milliVolts per metre a] find the thickness of the mica needed b] determine the area of the plate assuming its a two plate construction 17 November 2010 01:54 PM bheka Posts: 2 Joined: 16 November 2010 unfortunately we the lecturee hasnt bn forthcoming....otherwise from study Q=CV....C=[Relative pemeativity*d]/A.........now i saw a formula which talks of capacitance per unit area which is C=E/D.........am not sure what E stands for in this equation............bt C is capacitance and D is plates separtion =thickness of dielectric 19 November 2010 04:50 PM simonevans Posts: 1 Joined: 19 March 2003 Hi, This is reasonably straight forward. Firstly, I'm quite sure the dielectric strength of mica is not 50 mV/m. It is more like 50MV/m so there may be a slight mistake there. To find thickness use: E=V/d E = 50MV/m, V = 1.25 kV For the area use, C= eps.A/d Use d from part a and find out what the rel. perm is for mica. Something like 7 I think. C is given in the question. Hope that helps.
 IET » Electronic engineering » capacitors,dielectrics.......help me out Topic Tools
Statistics