# AQA AS Physics Electric Current

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• Electric Current
• Component and their characteristics
• Potential difference and Power
• Electrical power and Current
• Work done = QV = (I?t) V = IV ?t
• P = IV
• Energy and Potential differece
• Potential Difference is defined as the work done (or energy transferred) per unit charge.
• V = W / Q
• The mf of a source of electricity is defined as the electrical energy produced per unit charge passing through the source.
• Resistance
• Ohm's law
• It states that the pd across a metallic conductor is proportional to the current through it, provided that the physical conditions to not change.
• Resitivity
• ? = RA / L
• Resistance
• The resistance of any component is defined as: the pd across the component / the current trough it.
• R = V / I
• Superconductors
• A superconductor is a wire ot a device made of material that has zero resistivity at and below a critical temprature that depends on the material.
• Current and Charge
• ?Q = I?t
• I = ?Q/?t
• Work done = QV = (I?t) V = IV ?t
• Resistance
• The resistance of any component is defined as: the pd across the component / the current trough it.
• R = V / I