AQA GCSE Reasons for using transformers(Physics)
Reasons for using transformers
Electricity is distributed from power stations across a national grid to our homes.
Electricity from the power station will pass through a step up transformer which increases the potential difference from 25,000V to 400,000V.
Electricity is then transmitted as a high potential difference, low current.
Finally, the electricity will pass through a step down transformer to decrease the potential difference from 400,000V to 230V to supply homes.
Why transmit electricity as a high potential difference, low current.
Keeping the potential difference high, means that the current is low.
A low current makes the transmission of electricity more efficient.
If the current is higher, then more of the electrical energy is converted into thermal energy, which initially heats the wires, then the wires radiate the heat energy to the surroundings.
Another key advantage of using lower currents is that thinner cables can be used, which is cheaper.
Relating the use of transformers to equations.
Power = Potential difference x current.
For us to deliver a set amount of power, if we increase the potential difference, then the current will decrease.
If we want to deliver 1000W of power:
Power = Potential difference x current
1000W = 1000V x 1A
or
1000W = 100V x 10A
Again, keeping the potential difference high, reduces current, makes transmission of electricity more efficient.
Power of heat loss = Current2 x Resistance
This equation will calculate power of heat loss for transformer if we set resistance to be 1 ohm in both cases
When current is 1A:
Power of heat loss= 12A x 1 ohm = 1W
When the current is 10A:
Power of heat loss= 102A x 1 ohm = 100W
So, you can see that as the current increases, the power loss due to the heating effect increases significantly!
Practice Questions
1.Describe the journey of electricity from a power station to our homes.
2. Explain the advantage of transmitting electricity as a high potential difference, low current.
3. A current through a wire is doubled, predict how this would affect the power loss in terms of heat from the wire.
Absorption and Emission of EM Radiation
JJ Thomson and Plum pudding model
Ernest Rutherford and the Nuclear Model
Niels Bohr changing the Nuclear Model
Discovering the Proton and Neutron
Measuring radiation from radioactivity
Radiation types and properties
Random nature of radioactive decay
Radioactive contamination or irradiation
Hazards of contamination and irradiation
Studies on the effects of radiation on humans
Different half lives of radioactive isotopes
Nuclear Fission Chain Reaction
Writing nuclear fission equations
Drawing ray diagrams for a concave lens
Drawing Ray Diagram to produce a virtual image for a convex lens
Drawing ray diagram to produce a real image for a convex lens.
Specular and Diffuse Reflection
Seeing Coloured Objects Part 2
Viewing objects through coloured filters
Transparent, Translucent and Opaque
Accordion Content
Accordion Content