ELECTRCITY

• what is electric current?

  a flow of electrical charge
• what is the unit for electric current?

  ampere, A
• what is potential difference?


  the driving force that pushes the charge around (voltage)
• what is the unit for potential difference?


  volts, V
• what is resistance?


  anything that slows the flow down
• what is the unit for resistance?

  ohms, Ω
• what is ohm's law?

  the greater the resistance across a component, the smaller the current that flows (for a given voltage across a component)
• what is the rate of charge?


  the size of the current
• what is the equation for charge flow?

  charge flow = current × time

  Q = I × t
• what is the diagram for a cell?

  
• what is a battery?


  a number of electrical cells in series
• what is the diagram for a battery?

  
• what is a diode?

  a component that only allows current to flow in one direction
• what is the diagram for a diode?

  
• what is a variable resistor?

  a component that are altered continually as they work
• what is the diagram for a variable resistor?

  
• what is an LED?


  a diode that emits light when it conducts
• what is the diagram for an LED?

  
• what is a filament lamp?


  a common type of light bulb
• what is the diagram for a filament lamp?

  
• what is the diagram for an open switch?

  
• what is the diagram for a closed switch?

  
• what is a fuse?

  a wire which melts if the current is too high
• what is the diagram for a fuse?

  
• what is a voltmeter?


  a device used to measure voltage
• what is the diagram for a voltmeter?

  
• what is an ammeter?

  a device used to measure current
• what is the diagram for an ammeter?

  
• what is a thermistor?


  a temperature dependent resistor
• what is the diagram for a thermistor?

  
• what is an LDR?

  a light dependent resistor
• what happens to the resistance as the current through an ohmic resistor changes?


  remains constant

  
• what happens to the resistance of a bulb as temperature of the filament increases?

  the resistance increases

  
• what happens to the resistance of a thermistor as the temperature increases?

  the resistance decreases
• what happens to the resistance of a light dependent resistor as the intensity of light increases?

  the resistance decreases
• what are the rules for a series circuit?

  - I1 = I2 = ...

  - Vtotal = V1 + V2 + ...

  - Rtotal = R1 + R2
• what happens when you add resistors to a series circuit?


  total resistance increases, total current decreases
• what happens when you add resistors to a parallel circuit?

  total resistance decreases, total current increases
• what does dc stand for?


  direct current
• what is direct current?

  current that flows in one direction