# Electricity Flashcards Preview

## Physics-P1 > Electricity > Flashcards

Flashcards in Electricity Deck (19)
1
Q

What is charge flow and how do you calculate it + unites

A

the rate of flow of electrical charge
charge flow = current x time
coulombs

2
Q

what is resistance and what happens if it is high

A

Resistance is the measure of how it resists the flow of charge
The higher the resistance:
the more difficult it is for the charge to flow
the lower the current

3
Q

what is potential difference and how is it calculated + units

A

potential difference tells us the difference in electrical potential from one point in a circuit to another (an electrical push) - (the opposite of resistance)
potential difference = current x resistance
volts

4
Q

what does a straight line, steep gradient, and shallow gradient represent through a potential difference graph

A

A straight line = the voltage and current are directly proportional
A steep gradient = low resitance
A shallow gradient = high resistance

5
Q

How are resistors, filament lamps and diodes represented on graphs

A

resistors = straight line graph (linear)
Filament Lamp= curved graph
Diodes = horizontal line along the x-axis

6
Q

Four features of a parallel circuit (current , PD, total resistance)

A
• The PD across all components is the same (v)
• The total current drawn from the power supply is the sum of the current through separate components
• The total resistance of two resistors is less than the resistance of the smallest individual resistors
• Adding resistors in parallel reduces total resistance
7
Q

Four features in a series circuit (current, PD, total resistance)

A
• There is the same current through each component
• The total PD across of the power supply is shared through components
• The total resistance of the components is the sum of resistance through each component
• Adding resistors in parallel increases the total resistance
8
Q

How is power in circuits calculated

A

power = potential difference x current
power = (current)’2 x resistance
watts

9
Q

features of a direct current and where is it used

A
• has a potential difference that is always positive or negative
• is the type of current used by cells and batteries
10
Q

features of an alternating current and use

A
• has a potential difference that alternated form positive to negative
• is the type of current used in main electricity
11
Q

What is the current and function of each wire in a plug

A
```Earth
- green/yellow
-safety wire to stop the appliance becoming live
Neutral
-blue
-completes the circuit and carries current away from appliance
Live
-brown
-carries current to the appliance```
12
Q

Why can someone still get electrocuted when touching a live wire even when off

A

they will make a pathway for the current to flow by creating a potential difference from the live wire to the earth.

13
Q

What is power and how can it be calculated

A

Power is the rate at which energy is transferred and work is done
power = energy transferred / time
power = work done / time

14
Q

What is efficiency and how is it calculated

A

Efficiency is the rate of useful energy out to total energy in
efficiency = useful energy / total energy transfer

15
Q

what is work done and how is it calculated

A

work is done when charge flows
energy transferred = power x time
energy transferred = charge flow x potential difference

16
Q

How is the national grid efficient

A

-Power station
using a small number of large power stations as most use steam turbines which are more efficient at higher temperatures
-Step-up transformers
reduces the heating effect caused by current flowing through transmission cables

17
Q

What happens during friction

A
• friction moves negatively charged electrons from one material to another
• the object that gains electrons becomes negatively charged
• the object that looses electrons becomes positively charged
18
Q

Why is friction not seen with conductors

A

as they conduct the charge to earth so it cannot build up

19
Q

Why is an electrical spark caused

A

as the charge on an isolated object increases the potential difference between the objects and earth increases
- when the potential difference becomes high enough, the spark may jump across the gap form any conductor near it