Electricity 0.0 / 5 ? PhysicsElectricityA2/A-levelAQA Created by: Hlm153Created on: 22-02-20 09:40 Definition of current Rate of flow of charge, measured in Amps. 1A = 1C/s 1 of 19 Definition of potential difference Energy transferred when 1C of charge passes between 2 points. 1V=1J/C 2 of 19 Definition of a superconductor A material that has zero resistivity when cooled below a critical (transitional) temperature 3 of 19 What does a potential divider do? Taps off fraction of voltage available 4 of 19 Emf Electrical energy supplied to circuit per unit of charge 5 of 19 What is the transitional temperature of most normal conductors? -263 C (10 Kelvin) 6 of 19 Uses of superconductors Power cables and Electromagnets 7 of 19 What is the resistance of an ammeter? 0 8 of 19 What is the resistance of a voltmeter? Infinitely high 9 of 19 How does potential difference behave in a series circuit? VT = V1 + V2 + V3 10 of 19 How does resistance behave in a series circuit? RT = R1 + R2 + R3 11 of 19 How does current behave in a series circuit? Same everywhere 12 of 19 How does potential difference behave in a parallel circuit? Same on each branch 13 of 19 How does resistance behave in a parallel circuit? 1/RT = 1/R1 + 1/R2 + 1/R3 14 of 19 How does current behave in a parallel circuit? IT = I1 + I2 + I3 15 of 19 What are Kirchoff's laws? 1 - Net flow of current into a juntion = 0, 2 - Around a closed loop in a circuit sum of p.d. is 0 16 of 19 What is a cell? A source of emf with it's own internal resistance 17 of 19 What happens to V as R decreases and I increases? V decreases because more of the cell's emf is needed to push the current through its internal resistance 18 of 19 What does infinite resistance give? emf 19 of 19
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