Physics - electricity in the homes

What is the national grid?

A nationwide series of cables and transformers

What do step up and step down transformers do?

Step up - Increase PD, decrease current which reduces the heat loss/ energy loss to be more efficient
Step down - do the opposite

Definition of Direct current (DC) + draw and label a graph (paper flashcards)

Current travels in 1 direction

Definition of Alternating Current (AC) + draw and label a graph. (paper fashcards)

Current changes direction.

What is an oscilloscope?

An oscilloscope is a device that allows you to see how voltage changes over time by displaying a waveform of electronic signals

What do each of the axis on the oscilloscope mean?

x axis - called time base - time for 1 complete wave from peak to peak. (use scale)

y axis - called y-gain shows the potential difference from the origin line to the peak of the wave. (use scale)

Frequency meaning and the Equation for frequency:

Number of times something happens in 1 second. (measured in Hz)

1/ time period

Label the number of the diagram:

Wire grip

Neutral wire (BL - Bottom left)

Earth wire - yellow/ green stripy wire

Live wire - brown wire (BR - Bottom right)

Fuse

What does the live wire do?

What is it’s pd?

Live wires carry the power from the source to a switch or appliance.

has an alternating pd of 230V from the mains supply, making it very dangerous.

What does neutral wire do?

Is neutral in charge/ no charge, which carries the circuit back to its original power source which is the ground at the substation

What does Earth wire do?

The earth wire is a safety wire to stop the appliance becoming live. It is connected to the Earth/ ground under your house.

Why does a plug have these materials?
Hard case
Pins
Inner wire
Wire coating

Hard case - made out of hard plastic Durable + doesn't conduct electricity

Pins - Brass - conductive + strong and rigid

Inner wire - copper - Conductive and bendy

Wire coating - plastic - so that the wires don't touch eatchother

What are 2 ways we can increase he brightness of a bulb?
What 2 factors do thee brightness of a bulb rely on?

1. Increase PD by adding another cell
Increase the current

2. PD AND current

What does 1kWhr equal in Energy?

(1kWhr \= 3.6 x 10^6 or 3.6 MJ)

Equation for calculating efficiency:

efficiency \= useful power(or energy)/ total power (or energy) x 100

(given in percentage)

Name all of the equations related to electricity: hint : P P E E V Q :

P = IV

P = I²R

E = Pt

E = QV

V = IR

Q = It