Physics Capacitors

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Capacitors

Kirchhoffs First Law of Capacitor

This law is based on the principle of conservation of charge .
i.e. at the junction `sum q = 0`
This law is useful in determining the nature of charge on an unknown capacitor plate.

As no charge can accumulate at the junction O, so if `x` is charge on plate 1 of C, then
from Fig `-q_1 + q_2 +x = 0`

`x = q_1 - q_2`

i.e. plate 1 has a charge `(q_1 - q_2)` and plate 2 has a charge `-(q_1 - q_2)`

This law is based on the principle of conservation of charge .
i.e. at the junction `sum q = 0`
This law is useful in determining the nature of charge on an unknown capacitor plate.

As no charge can accumulate at the junction O, so if `x` is charge on plate 1 of C, then
from Fig `-q_1 + q_2 +x = 0`

`x = q_1 - q_2`

i.e. plate 1 has a charge `(q_1 - q_2)` and plate 2 has a charge `-(q_1 - q_2)`

Kirchhoffs Second Law or loop law

This law is based on the principle of conservation of energy.
In a closed loop , the algebraic sum of potential difference across each element of a closed circuit is zero.

`sum V = 0`

`text(Conventions Followed to Apply Loop Law)`

a) In a loop, across a battery, if we travel from -ve terminal of battery to the +ve terminal, there is a potential rise and a +ve sign is applied with voltage of the battery.

b) In a loop, across a battery , if we travel from +ve terminal of the battery to the -ve terminal , there is a potential fall and - sign is applied with voltage of the battery.

c) In a loop, across a capacitor, If we go from negative plate to the positive plate of the capacitor, there is a potential rise and a + sign is to be taken with potential difference across the capacitor `i.e. DeltaV = q/c`

This law is based on the principle of conservation of energy.
In a closed loop , the algebraic sum of potential difference across each element of a closed circuit is zero.

`sum V = 0`

`text(Conventions Followed to Apply Loop Law)`

a) In a loop, across a battery, if we travel from -ve terminal of battery to the +ve terminal, there is a potential rise and a +ve sign is applied with voltage of the battery.

b) In a loop, across a battery , if we travel from +ve terminal of the battery to the -ve terminal , there is a potential fall and - sign is applied with voltage of the battery.

c) In a loop, across a capacitor, If we go from negative plate to the positive plate of the capacitor, there is a potential rise and a + sign is to be taken with potential difference across the capacitor `i.e. DeltaV = q/c`

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