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Compare the expression for magnetic energy density with electrostatic energy density stored in the space between the plates of a parallel plate capacitor. |
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Answer» The enectrostatic energy stored `U=(1)/(2)(q^(2))/(C)=(q^(2))/(2epsilon_(0)A)xxd" …(i)"` (where C is the capacitance, `C=(epsilon_(0)A)/(d)`, q is the charge upon capacitor) Now the electric field in the space (between plates of capacitor) `E=(q)/(epsilon_(0)A)" ...(ii)"` From equation (i) and (ii), `U=(1)/(2)((q)/(epsilon_(0)A))^(2)xxepsilon_(0)xxAxxd` `rArr" "U=(1)/(2)epsilon_(0)E^(2)xx"Volume"` Hence `(U)/("Volume")=(1)/(2)epsilon_(0)E^(2)" ...(iii)"` This expression can be compared with magnetic energy per unit volume which is equal to `(B^(2))/(2mu_(0)).` ....(iv) |
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