Potential difference, current, resistance

• What is the equation that relates voltage, current, and resistance?

  v = ir
• What does the equation v = ir represent?

  Voltage equals current times resistance
• If a circuit has a current of 4 amps and a resistance of 2 ohms, what is the voltage?

  8 volts
• How do you find the resistance if you have a 24 volt battery producing 8 amps?

  Use r = v / i
• What is the resistance when using a 24 volt battery and 8 amps?

  3 ohms
• What happens to current when voltage increases while resistance remains constant?

  Current increases proportionally
• What does a graph of current against potential difference show when resistance is constant?

  It shows a straight line
• What does a negative part of the current versus potential difference graph indicate?

  Voltage and current are negative
• How does the steepness of the line on a current versus potential difference graph relate to resistance?

  Less steep for larger resistors
• What happens to the required potential difference with a smaller resistor?

  Less potential difference is needed
• What assumption is made regarding temperature in these circuits?

  Temperature stays constant
• What effect does increasing temperature have on resistance?

  Resistance increases
• What is a filament lamp?

  A light bulb with a thin metal filament
• How does a filament lamp's resistance change as current increases?

  Resistance increases due to heating
• What do diodes do in a circuit?

  Allow current to flow in one direction
• What happens to current when potential difference is negative in a diode?

  No current flows
• What is the resistance behavior of diodes in reverse direction?

  High resistance prevents current flow
• What are the key characteristics of current versus potential difference graphs for resistors?

  • Straight lines indicate constant resistance
  • Steeper lines indicate lower resistance
  • Less steep lines indicate higher resistance
• What are the differences between filament lamps and diodes in terms of current flow?

  Filament lamps:

  • Resistance increases with current
  • Emit light when heated

  
  

  Diodes:

  • Allow current in one direction only
  • High resistance in reverse direction