# 4.3 Electrical Circuits Flashcards Preview

## Physics A Level > 4.3 Electrical Circuits > Flashcards

Flashcards in 4.3 Electrical Circuits Deck (14)
1
Q

What is Kirchoff’s second law?

A

The total EMF across a circuit loop is equal to the sum of potential differences across devices in that loop

2
Q

What does Kirchoff’s second law conserve?

A

Energy

3
Q

What happens when cells are added in series? (2)

A

Current increases

Voltage increases

4
Q

What happens when cells are added in parallel? (3)

A

Current stays the same
Voltage stays the same
Cells last longer

5
Q

What happens when resistors are added in series? (3)

A

Voltage stays the same
Current decreases
R = R1 + R2

6
Q

What happens when resistors are added in parallel? (3)

A

Voltage stays the same
Current increases
1 / R = (1 / R1) + (1 / R2)

7
Q

Value of resistivity - conductors

A

In the order of 10^-8 ohm metres

8
Q

Value of resistivity - insulator

A

In the order of 10^16 ohm metres

9
Q

Value of resistivity - semiconductor

A

10^-8 to 10^16 ohm metres

10
Q

What is internal resistance?

A

The resistance within a source of EMF, reducing the voltage supplied to the rest of the circuit (r)

11
Q

What are lost volts?

A

The PD used on the internal resistance

12
Q

What is the internal resistance equation?

A

E = V + Ir
E: EMF
V: terminal PD (available for use)
Ir: lost volts

13
Q

What are the advantages of using a rheostat in a potential divider circuit? (2)

A

There is a full range of PD across resistor

Can be used to find IV characteristics

14
Q

How are resistance and voltage divided in a potential divider circuit? (2)

A

R1:R2 = V1:V2

The PD across each component is proportional to its resistance