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CP11F
GCSE Combined Science Physics
Question | Answer |
---|---|
What is the national grid ? | This is system of wires and cables that bring electricity from the power system to our homes and other buildings. |
Where is energy lost in the national grid? | By heating of the transmission lines. |
What happens if the voltage (potential difference ) across the transmission wire is increased? | The current decreases. |
Why do we transmit electricity at low currents? | "Less energy is dissipated at heat to the surrounding air and it is more efficient. |
" Current which regularly changes direction is called… | alternating current |
An example of alternating current is…? | mains electricity |
Current which flows in one direction is…? | direct current |
An example of direct current is… | batteries |
What is the potential difference of mains electricity in the UK? | 230V |
What is the frequency of the alternating current in UK mains electricity? | 50Hz |
The national grid consists of…? | Cables and transformers |
Are power stations par of the national grid? | no |
What does a step up transformer do? | Increases p.d. |
What does a step down transformer do? | reduces p.d. to 230 V |
Why are transformers used? | reduce current so that less heat is lost in cables, increases efficiency |
What are the names o the two wires in a transformer? | Primary and Secondary coil |
A step-up transformer has more turns in the _______ coil. | Secondary coil |
A step-down transformer has more turns in the _______ coil. | Primary Coil |