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A 2400 pF air-gap capacitor is connected to a 6.4 V battery. If a piece of mica is placed between the plates, how much charge will flow from the battery?

Respuesta :

Explanation:

It is given that,

Capacitance, [tex]C=2400\ pF=2.4\times 10^{-9}\ F[/tex]

Potential difference, V = 6.4 volts

Initial charge, [tex]Q_1=CV[/tex]

[tex]Q_1=2.4\times 10^{-9}\ F\times 6.4\ V[/tex]

[tex]Q_1=1.53\times 10^{-8}\ C[/tex]

When the mica is introduced between the plates of capacitor, the capacitance increases by a factor of k. The dielectric constant of mica lies in between 6 - 8. Let k = 7 (say)

New capacitance, [tex]C'=2.4\times 10^{-9}\ F\times 7=1.68\times 10^{-8}\ F[/tex]

Final charge, [tex]Q_2=1.68\times 10^{-8}\ F\times 6.4\ V[/tex]

[tex]Q_2=1.07\times 10^{-7}\ C[/tex]

[tex]Q_2-Q_1=1.07\times 10^{-7}\ C-1.53\times 10^{-8}\ C=9.17\times 10^{-8}\ C[/tex]

So, when mica sheet is introduced, more charge will flow out of the battery. Hence, this is the required solution.