# aqa physics circuits

PLEASE NOTE THIS I A BAISIC MINDMAP AND IS NOT ALL YOU NEED TO KNOW ABOUT CIRCUITS

• CIRCUITS
• Current and potential difference
• current is the flow of electric charge round a circuit
• current will only flow through a component if there is a potential difference across it
• potential difference is the driving force pushes the current around (in VOLTS)
• the greater the resistance across a component the smaller the current that flows
• CURRENT = CHARGE / TIME
• P.D = WORK DONE / CHARGE
• CURRENT x RESISTANCE
• THE BASICS
• the ammeter
• measures current in AMPS
• must be placed in a series
• can never be parallel to the volmeter
• the volmeter
• measures potential difference in VOLTS
• must be placed in parallel around the component not the variable resistor or the battery
• very basic circuits are used for V-I graphs
• as you vary the variable resistor it alters the current flowing through a circuit
• GRAPHS
• the current through the resistor is directly proportional to the P.D
• as the temperature of the filament increases the resistance increases
• RESISTANCE ALWAYS INCREASES WITH TEMPRATURE
• current will only flow through a diode in one direction. It has a very high resistance in the opposite direction
• SERIES CIRCUITS
• P.D. is shared between the components
• current is the same everywhere
• total resistance is the resistance added up throughout the whole circuit
• cell voltages are added up
• PARALLEL CIRCUITS
• P.D, is the same across all components
• current is shared between the branches