Flashcards in Electricity Deck (38)

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1

## Current is...

### ...rate of flow of charge.

2

## Current is measured in what?

### Amperes.

3

## Equation linking current, charge and time:

### I=ΔQ/Δt

4

## Kirchhoff's current law:

### The total current flowing into a point is equal to the current flowing out of a point.

5

## What is Kirchhoff's current law based on?

### Conservation of charge principle. Charge is conserved in a circuit meaning current is also conserved.

6

## Potential difference is the energy per...

### ...coulomb of charge.

7

## Potential difference is a measure of what?

### The amount of energy per unit of charge transferred between two points in a circuit.

8

## Equation linking potential difference, energy and charge:

### V = W/Q

9

## In series potential difference across the components...

### ...adds to the potential difference across the circuit.

10

## In parallel potential difference...

### ...remains the same for every branch across the circuit (it is equal throughout).

11

## Kirchhoff's potential difference law:

### States that around any closed loop in a circuit the sum of the potential difference across all components equals the potential difference across the supply.

12

## What is Kirchhoff's potential difference law based on?

### Conservation of energy principle.

13

## Ohm's Law is stated as:

### The voltage drop across an ohmic conductor is proportional to the current flowing through it provided temperature remains constant.

14

## Formula for resistance linking potential difference and current:

### R = V/I

15

## Power is the rate of...

### ...transferring energy.

16

## Equation for power linking energy and time:

### P = W/t

17

## Equation for power linking current and potential difference:

### P = IV

18

## Equation for energy linking current, potential difference and time:

### W = IVt

19

## Equation for power linking current and resistance:

### P = I^2R

20

## Factors that affect resistivity:

###
Material

Cross-sectional area

Length

Temperature

21

## As the length of material increases, what happens to resistivity?

### It also increases.

22

## As cross-sectional area increases what happens to resistivity?

### Resistivity decreases.

23

## Equation for resistance linking length, cross-sectional area and resistivity:

### R = ρl/A

24

## A potentiometer is a device that does what?

### It is a device that provides a pd ranging from 0V up to the voltage of the supply.

25

## Equation for potentiometers.

### Vout/Vs=x/l

26

## Equation for drift velocity.

###
I=nAvq

I is in A

v in ms^-1

A in m^2

n in m^-3

q in C

27

## What is resistivity?

### The resistance of a 1m^2, 1m long piece of material.

28

## EMF stands for...

### ...electromotive force.

29

## A cell has an internal what?

### Resistance.

30