Electricity

• What is current?

  The flow of electrical charge
• What electric charge flow measured in?

  Coulombs (C)
• What is current measured in?

  Amps (A)
• What is the equation for charge flow?

  charge flow = current x time (in seconds)
• What happens to the current in a single, closed loop of a circuit?

  It stays the same
• What is the component name of the symbol below?

  This is an open switch

  
• What is the name of the symbol below?

  This is a closed switch

  
• What is the name of the symbol below?

  This is a cell

  
• What is the name of the symbol below?

  This is a battery

  
• What is the name of the symbol below?

  This is called a diode

  
• What is the name of the symbol below?

  This is a resistor

  
• What is the name of the symbol below?

  This is a variable resistor

  
• What is the name of the symbol below?

  This is a bulb (Can also be called a lamp)

  
• What is the name of the symbol below?

  This is a fuse

  
• What are the names of the 2 symbols below?

  This is a voltmeter and ammeter

  
• What is the name of the symbol below?

  This is a thermistor

  
• What is the name of the symbol below?

  This is called an LDR

  
• What is the resistance of a component?

  A measure of how it resists the flow of charge
• How does a high resistance effect current?

  It lowers the current - It makes it more difficult for charge to flow
• What is resistance measured in?

  ohms
• What is potential difference / voltage?

  the difference in electrical potential between two points in a circuit - can be thought of as an electrical push
• How does a high voltage / potential difference affect current ?

  It increases the current - the charge flow across the component become greater
• What is the equation for potential difference?

  potential difference = current x resistance
• What do potential difference - current graphs show?

  The relationship between the potential difference and current in a component
• What type of line indicates a directly proportional voltage and current?

  A straight line
• What type of gradient indicates a low resistance?

  A steep gradient - A large current will flow for a small potential difference?
• What type of gradient indicates a high resistance?

  A shallow gradient - A large potential difference is needed to produce a small current
• What is an ohmic conductor?

  A resistor where the current is directly proportional to the potential difference at a constant temperature
• What happens to the resistance in an ohmic conductor?

  The resistance remains constant as the current changes
• What component does the graph below show?

  This shows an ohmic conductor

  
• What happens to the resistance in a filament lamp?

  The resistance increases as the current increases - This is because as the current increases, the temperature of the lamp also increases
• Which component does the graph below show?

  This shows a filament lamp

  
• Why does the current in a diode only flow in one direction?

  The diode has very high resistance in the reverse direction
• What component is shown in the graph below?

  This shows a diode

  
• What happens to the resistance in thermistors?

  The resistance decreases as the temperature increases
• Thermistors are useful in temperature control circuits. Give 2 examples of this

  In a circuit for a thermostat that turns a heater off at a particular temperature OR a circuit for an indicator light that turns on when a system is overheating
• What happens to the resistance in an LDR?

  The resistance decreases as the light intensity increases
• LDR's can be used when automatic light control is needed. Give 2 examples of this

  Street lights and cameras - to determine if a flash is needed
• Complete the sentence

  Series circuits have no branches - the current can only flow in one path
• Describe the current in series circuits

  In a series circuit, the current is the same all the way round - at each component