# Electricity - Section 6 AQA

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• Created by: Alicia_H
• Created on: 16-10-16 08:17
• Electricity
• Current
• I=Q/t
• I=Current (A,Amps)
• Measured using ammeter in series
• Ammeter = zero resistance
• Q=Charge (C,Coulomb)
• The rate of flow of electrons
• t=Time (s,seconds)
• Potential Difference
• V=W/Q
• V=Voltage  (V,Volts)
• 1V=1J/C
• Measured using Voltmeter in parallel
• Voltmeter = infinitely resistant
• Q=Charge (C,Coulomb)
• W=Work done (J,Joules)
• Resistance
• R=V/I
• I=Current (A,Amps)
• R=Resistance (?, ohms)
• Ohmic Conductors
• Ohms Law: Provided physical conditions remain constant the current through an ohmic conductor is directly proportional to the current through it
• I is directly proportional to V
• Graph is a straight line through the origin
• Resistors
• Variable Resistor
• Resistance can be varied
• Thermistor
• Resistance decreases as temperature increases
• V=Voltage (V,Volts)
• Resistivity
• resistivity =(RA)/l
• l=Length (m,metres)
• R=Resistance (?, Ohms)
• Resistivity     (?m, ohm-meters)
• A=cross-sectional area (m2)
• Super-conductors
• Zero Resistivity
• Uses:     Power Cables Electromagnet Fast Circuits
• Power
• P=VI
• P=I²R
• Electrical Energy
• E=VIt
• E.m.f and Internal Resistance
• emf=E/Q
• emf=I(R+r)