resistance of wires

• What is the focus of this investigation?

  The resistance of a wire
• What is the aim of the investigation?

  To investigate the relationship between wire length and resistance
• Why is copper wire not used in this experiment?

  Its resistance is too small to measure
• Why are wires not perfect conductors of electricity?

  They have some resistance
• How will you measure the wire's resistance in this practical?

  By measuring current and potential difference
• What type of wire is used in this experiment?

  Nichrome wire
• How should the length of nichrome wire be measured?

  Using a meter ruler
• What components are needed to set up the circuit?

  Battery, ammeter, resistance wire
• What are the variables in the investigation?

  • Independent variable: Length of the wire
  • Dependent variable: Resistance of the wire
  • Control variables:
  • Thickness of the wire
  • Material of the wire
  • Temperature of the wire
• What is the first connection made in the circuit?

  Battery to ammeter
• Why is a double length cable used in the circuit?

  To ensure easy connections for longer wires
• Where is the first crocodile clip attached?

  At the zero mark of the meter ruler
• What happens to the second crocodile clip during the experiment?

  It moves to test different wire lengths
• What is the maximum length of wire tested in this experiment?

  100 centimeters
• Why should the wire be taut during measurements?

  To avoid errors in length measurement
• What is the initial voltage reading at 100 cm?

  4.71 volts
• What happens to the voltage as the length of wire decreases?

  The voltage reading drops
• How does the current change as the length of wire decreases?

  The current generally increases
• What is the current reading at 30 cm?

  0.20 amps
• How is resistance calculated in this experiment?

  Resistance = Voltage / Current
• What should be done after taking all measurements?

  Disconnect the power supply
• Why is it important to disconnect the circuit between readings?

  To prevent overheating of the wire
• What are the steps to plot the resistance against length graph?

  1. Calculate resistance for each length.
  2. Plot resistance on the y-axis.
  3. Plot length on the x-axis.
  4. Draw a line of best fit.
  5. Ideally, it should be a straight line.
• What should the ideal line of best fit indicate on the graph?

  A straight line with a positive gradient
• What is the relationship between resistance and length of wire?

  Resistance increases with length