Question

How much energy is stored by the electric field between two square plates, 8.5 cm on a side, separated by a 2.5-mm air gap? The charges on the plates are equal and opposite and of magnitude 14 nC .

Answer 1

Answer:

The stored energy is $3.83\times10^{-6}\ J$.

Explanation:

Given that,

One side of square plates = 8.5 cm

Distance = 2.5 mm

Charge = 14 nC

We need to calculate the energy stored

The energy is stored by the electric field between two square plates is defined as,

$U=\dfrac{1}{2}\times\epsilon_{0}\times(\dfrac{q}{A\epsilon_{0}})^2\times A\times D$

$U=\dfrac{1}{2}\times\dfrac{q^2}{A\epsilon_{0}}\times D$

We calculate the area iof square plates

$A=(8.5\times10^{-2})^2$

$A=0.007225=72.2\times10^{-4}\ m^2$

Now, put the value into the formula

$U=\dfrac{1}{2}\times\dfrac{(14\times10^{-9})^2}{72.2\times10^{-4}\times8.85\times10^{-12}}\times2.5\times10^{-3}$

$U=3.83\times10^{-6}\ J$

Hence, The stored energy is $3.83\times10^{-6}\ J$.