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Question
In a parallel plate capacitor with air between the plates, each plate has an area of 6 × 10−3 m2 and the distance between the plates is 3 mm. Calculate the capacitance of the capacitor. If this capacitor is connected to a 100 V supply, what is the charge on each plate of the capacitor?
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Solution
Given: A = 6 × 10−3 m2
V = 100 volts
d = 3 mm = 3 × 10−3 m
To find: Capacitance C = ?
Charge on each strip = ?
Formula: Capacitance (C) = `(ε_0 A)/d`
= `(8.854 xx 10^-12 xx 6 xx 10^-3)/(3 xx 10^-3)`
= `(53.124 xx 10^-15)/(3 xx 10^-3)`
= 17.7 × 10−12
= 1.77 × 10−11
Charge on a capacitor q = C × V
= 1.77 × 10−11 × 100
= 1.77 × 10−9 C
= 1.77 nC
∴ Charge on one strip = + 1.77 × 10−9 C
Charge on the second strip = −1.77 × 10−9 C
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