P1: Electric Circuits, Resistor Networks and Power
Official Cambridge & Imperial ESAT specification requirements for Electric Circuits, Resistor Networks and Power on the Physics paper. Understand the syllabus boundaries, spot distractor traps engineered by examiners, and master the 2-step Sub-90 shortcuts that compress solve time well below the 88.8-second cutoff.
Official Syllabus Subtopics
Requirements specified in the UAT-UK framework
- 1Current I = ΔQ/Δt, potential difference V = W/Q, Ohm’s law V = IR
- 2Series resistor circuits (Rₜₒₜ = R₁ + R₂) and parallel circuits (1/Rₚ = 1/R₁ + 1/R₂)
- 3Product-over-sum parallel rule: Rₚ = (R₁ × R₂) / (R₁ + R₂)
- 4Potential divider ratio: V(out) = V(in) × (R₂ / (R₁ + R₂))
- 5Sensors: LDRs (light up, resistance down) and NTC thermistors (temp up, resistance down)
- 6Electrical power: P = IV = I²R = V²/R and energy E = Pt = VIt
- 7Internal resistance and terminal potential difference: V = ε - Ir
Sub-90 Exam Speed Tips
How top candidates solve this spec under the 88.8s clock
Always use product-over-sum Rₚ = (R₁ × R₂) / (R₁ + R₂) for 2 parallel resistors instead of reciprocating fractions.
In a potential divider, the output voltage is directly proportional to that resistor’s share of total resistance.
Examiners engineer distractor options using common algebraic expansions and sign slips. Always test structural ratios or invariants before calculating arithmetic values.
Tested Topics in Specification P1
Master the individual question patterns and Sub-90 shortcuts for this specification.
Series-Parallel Resistor Networks, Potential Dividers & Variable Sensor Meter Tables
Use the product-over-sum shortcut Rₚ = (R1*R2)/(R1+R2) (and R/n for n identical parallel resistors). In meter trend tables, take the extreme limit R(var) -> infinity (open circuit) to read ammeter/voltmeter changes in 5 seconds.
Electrical Power Dissipation (P = IV = I²ᴿ = V²/R), Grid Efficiency & Energy (E = VIt)
Match the formula to the invariant: use P = I²*R for series components and transmission lines (same I); use P = V²/R for parallel branches connected across a fixed supply (same V).
Ready to Master Specification P1 Under Exam Conditions?
Practice timed questions under the authentic Pearson VUE interface with live split stopwatch pacing, dry-wipe scratchpad, and distractor forensics.