# AS Physics, Unit 2 Summary, Edexcel

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• Created by: Kizzy
• Created on: 12-02-13 16:56
• Unit 2
• Electricity
• Definitions
• Resistance  - opposition to the flow of charge
• Potential difference - amount of energy transferred per unit of charge
• Charge - property of matter upon which electric force acts
• Current - the rate of flow of charge
• Resistivity - the amount of resistance given from a unit volume of a substance
• Laws
• Kirchoff's Junction Law -  at a junction, the sum of the two split currents will total the sum of the input current
• Kirchoff's Loop Law - the sum of the potential difference across every component of a circuit totals to the sum of the input voltage of the cell
• Ohms Law - Given that the temperature and other physical properties remain constant, the current through a wire is proportional to the potential difference across its ends
• Symbols and Units
• Potential difference - Volts (V)
• Current (I) - Amperes (A)
• Charge  (Q) - Coulombs (C)
• Resistance (R) - Ohms ?
• Equations
• Voltage = Work/Charge
• Power = Voltage x Current
• Waves
• Types
• Standing (two waves with equal frequency and wavelength moving in opposing directions across the same medium