Return to 2 Electricity – Part A “Units”

2 Electricity – Part B “Mains”

Aims…

2.1 use the following units: ampere (A), coulomb (C), joule (J), ohm (Ω), second (s), volt (V), watt (W).

2.2 understand how the use of insulation, double insulation, earthing, fuses and circuit breakers in a range of domestic appliances.

2.3 understand why a current in a resistor results in the electrical transfer of energy and an increase in temperature, and how this can be used in a variety of domestic contexts

2.4 know and use the relationship:  

power = current × voltage  

P = I × V   or P=VI

and apply the relationship to the selection of appropriate fuses

2.5 use the relationship between energy transferred, current, voltage and time:

energy transferred = current × voltage × time

E = I × V × t   OR     E  =VIt

2.6 know the difference between mains electricity being alternating current (a.c.) and direct current (d.c.) being supplied by a cell or battery.

Resources….

Use this PowerPoint & Quiz for a quick review…

Video Clips…

 

Resistance Heating: It is useful to think about Power is converted in an oven heating element. P = VI or Ploss = I2R  so in this case we are trying to transfer energy to the surroundings as radiation (IR) by heating.

AC v DC: It is useful to look at the flow of electricity from a set of DC cells OR and AC power pack (note the power pack can also give out smoothed DC.

3 Pin Plug: This small equipment board shows what happens if you connect yourself to the wrong parts of a 3 pin plug. It should “burn” or “melt” the fuse this stop the circuit working..

Fuse Wire: This is a bigger version of what happens when too much current in Amperes flows in a circuit.

Transformer Coils: This transformer coil shows what happens when you step down the potential difference and increase the current. 

Circuit Breaker: A breaker in this case stops current flowing just like a fuse. However, it relies on an electromagnet which then can be reset when the current returns to normal.

Alarm Bell: This simple application of an electromagnet shows how when the circuit is broken the attraction stops and then the circuit is remade again and the cycle continues.

Electricity Meters and Bills: Everyone needs to know how to read one and understand what you pay and why!

Generation of AC: At the Hoover Dam we generate AC electricity, this video explains why it is AC

National Grid: A short video to explain how the energy is delivered to our homes.

 

Resistance heating with SMEG cooking element

Disclaimer: please never try this at home 40A from a cooker will kill you on first touch!

This is a video to show you how a cooker element transformed energy via
electrical mechanisms to Infra Red radiation which cooks your food. This element is usually covered by a plate which I took out to change the element and do a deep oven clean.Show More

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