V = IR Equation & Current/Potential Difference Graphs

• 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 a current of 8 amps?

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

  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 straight lines
• What does a steeper line on a current versus potential difference graph indicate?

  A smaller resistor is present
• What happens to the resistance if the temperature increases in a circuit?

  Resistance increases
• Why do filament lamps have a less steep curve at higher currents?

  Resistance increases due to heating
• What is the function of a diode in a circuit?

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

  No current flows
• What are the characteristics of current versus potential difference graphs for resistors?

  • Straight lines indicate constant resistance
  • Steeper lines indicate smaller resistors
  • Less steep lines indicate larger resistors
• What are the effects of temperature on resistance in electrical circuits?

  • Increased temperature raises resistance
  • Higher currents can cause wires to heat up
  • Resistance may not remain constant
• How do filament lamps and diodes differ in their current-voltage characteristics?

  Filament lamps:

  • Resistance increases with current
  • Curve becomes less steep at higher currents

  
  

  Diodes:

  • Allow current only in one direction
  • No current flows when potential difference is negative