CAIE IGCSE Physics 4.5.6.8 Recall Use P I2r to Explain Why Questions

Learn why raising transmission voltage lowers current and reduces resistive power loss in cables.

Exam points

explain why high-voltage transmission reduces current and cable power loss
apply P=I²R and V=IR relationships to transmission-loss calculations
relate transformer voltage changes to efficient transmission and substation distribution

[Maximum number: 3]

Electricity is transmitted at high voltage.

Explain why a high voltage increases the efficiency of transmission even with thinner wires.
[Total: 8]

any three from:

- $P=I^{2} R$ OR power (loss) $=I^{2} R$

- (high voltage allows) low current (so at same power output, less power / energy lost)

- thin wires have high resistance (so more power / energy lost)

- (low) current has a greater effect (on efficiency) than (high) resistance (of the thin wires)

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CAIE IGCSE Physics 4.5.6.8 Recall Use P I2r to Explain Why Questions question 1