Part B · Investigation, power and safety Electricity and circuits mind map

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Part B · Investigation, power and safety Electricity and circuits mind map

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Core practical

Setup: Low voltage; ammeter series, voltmeter parallel; vary V
I–V readings: Paired readings / reversed polarity; I vertical, V horizontal
Wire investigation: Vary length; same material, thickness and temperature
Reliability: Low currents / switch off; secure contacts, ranges, repeats
Non-ohmic R: Use V/I at the operating point, not arbitrary tangent slope

Energy / power

Heating: Moving charges transfer energy to lattice; useful or unwanted
Electrical energy: E = VIt; J with V, A and s
Power: P = E/t = IV = I²R; 12 V × 2 A = 24 W
Fixed conditions: Fixed I: larger R raises P; fixed V: P = V²/R falls
Cables: Low-resistance materials / thick wire reduce unwanted heating

Supply / safety

DC / AC: DC fixed polarity; AC reverses; UK ≈230 V, 50 Hz, T = 0.02 s
Wires: Live brown; neutral blue; protective earth green / yellow
Fault protection: Earth path → high fault current → fuse / breaker disconnects
Live isolation: Switch / fuse in live; live-to-earth contact dangerous
Double insulation: No exposed earthed metal case needed; no mains experiments

Connections

Core practical → Energy / power: Paired voltage and current readings give power.
Energy / power → Supply / safety: Cable heating and fault currents require protection.