P2: Electricity

• An electric current is a flow of charge, measured in amps (A)
• The mains supply is 230 V (Volts) and 50 Hz (Hertz)
• Potential difference is the work done by a given amount of charge, between two points on a circuit
• Potential difference (voltage) is measured in volts (V) with a voltmeter
• When resistors are added to a circuit, the resistance increases, as the battery is having to push charges through more resistors
• An alternating current (H) is a current that changes direction continuously.
• The Mains Supply uses alternating current as it is cheaper to produce and easier to distribute
• A direct current is a current that flows in the same direction in a circuit.
• As light intensity increases, the LDR‘s resistance decreases, and the current increases.
• An open switch

  
• A closed switch

  
• A cell

  
• A battery

  
• A diode

  
• A resistor

  
• A variable resistor

  
• A LED (imagine there’s a circle around it)

  
• A lamp

  
• A fuse

  
• A voltmeter

  
• An ammeter

  
• A thermistor

  
• An LDR

  
• Electrons are negatively charged particles that transfer electricity through wires
• Charge is measured in coulombs (C)
• Resistance is a measure of how easily a charge can flow
• A high resistance means a low current
• In a series circuit, the current is the same everywhere, as there is only one path for the current to go.
• In a parallel circuit, the current splits between the paths, as there are multiple to go through.
• The total potential difference across all components in a series circuit must be equal to the supply voltage.
• When two or more cells are connected together they form a cell stack.
• Voltage = current x resistance (V = IR)
• Charge = Current x Time (Q = IT)
• Power = Current x Voltage (P = IV)
• Power = Current2 x Resistance (P = I2R)
• Energy = Power x Time (E = PT)
• Energy = Charge x Voltage (E = QV)