# Conservation of Charge & Energy in Circuits Flashcards Preview

## Physics - Topic 3 - Electric Circuits > Conservation of Charge & Energy in Circuits > Flashcards

Flashcards in Conservation of Charge & Energy in Circuits Deck (10)
1
Q

Is charge conserved in a circuit?

A

YES

2
Q

Is it TRUE that charge into a junction equals the charge out of the junction?

A

YES

3
Q

Define Current?

A

Current is rate of flow of charge

4
Q

What is Kirchoff’s 1st Law

A

The total current entering a junction = the total current leaving it

5
Q

What two values must be equal for energy to be conserved in a circuit?

A

E.M.F

Potential Difference

6
Q

What does Kirchoffs 2nd Law state?

A

Total E.M.F around a SERIES circuit = the sum of the PD’s across each component

(Energy is conserved)

7
Q

What is the equation for Resistance in a series circuit?

A

R (total) = R1 + R2 + R3

8
Q

What is the equation for Resistance in a Parallel circuit?

A

1/R (total) = 1/R1 + 1/R2 + 1/R3

9
Q

How to calculate the equation of a Series Circuit? R(total) = R1 + R2 + R3

A

1 - Same current at all points of the circuit (because there are no junctions)
2 - E.M.F is split between components (by Kirchoff’s 2nd Law) ℰ = V1 + V2 +V3
3 - V = IR so I is constant
4 - IR (total) = IR1 + IR2 + IR3
5 - Cancelling the I’s gives R (total) = R1 + R2 + R3

10
Q

How to calculate the equation of a Parallel Circuit? 1/R (total) = 1/R1 + 1/R2 + 1/R3

A

1 - Current is split at each Junction so I = I1 + I2 + I3
2 - Same PD across all components (Within a loop the E.M.F equals the sum of individual PD’s)
3 - V/R (total) = V/R1 + V/R2 + V/R3
4 - Cancelling the V’s gives

1/R (total) = 1/R1 + 1/R2 + 1/R3