# Circuits

• Created by: Clare
• Created on: 26-03-13 16:16
• Circuits
• Conductors
• Metals are good conductors because they have free electrons
• This means they are not bound to a particular atom and move at random throughout the metal
• Currrent
• Rate of flow of electric charge through a conductor
• Measured in amps
• Current is the same throughout the circuit
• Measured using an ammeter with low resistance so it doesn't affect the circuit's current
• Measures how many coulombs of charge pass through the lamp per second
• Charge
• Measured in Coulombs (C)
• Charge= current x time
• Voltage
• Strength of current flow around a circuit
• Tells us how much energy is transferred per coulomb of charge
• Measured on a voltmeter in PARALLEL
• Goes opposite component (light) in it's own section
• Voltmeters have a very high resistance and measure how many joules of energy are converted
• Circuit symbols
• Switch
• Fuse
• LED
• Lamp/ Bulb
• Variable resistor
• Diode
• Light Dependent Resistor (LDR)
• Cell
• Series
• The same current flows through all components
• Circuit connected in series
• E.g.: Fairy lights so replacing a bulb is safer as all lights have gone out
• Any break stops everything, all components get an EQUAL share of battery voltage (same brightness) but are less bright overall
• Parallel
• At certain points the current is split and can take 2 or more routes, after the 2 currents join together
• If components are identical the current will divide equally
• E.g.: Main sockets and lights in a house- they all receive full voltage and don't stop working if one fuse blows
• Advantages: Brighter, individual control, whole circuit doesn't break
• Total current= sum of all currents on seprate