Resistance

• What is the main focus of the practical investigation described in the video?

  The factors affecting the resistance of electrical circuits
• What equipment is used in the practical investigation of resistance?

  • Battery
  • Ammeter
  • Voltmeter
  • Length of wire
• How do you measure the current in the circuit during the experiment?

  Using the ammeter
• How do you measure the potential difference across the wire?

  Using the voltmeter
• What equation is used to calculate the resistance in the circuit?

  Resistance in ohms equals potential difference in volts divided by current in amps
• What factor are we investigating that affects the resistance of a circuit?

  The length of the wire
• How do you increase the length of the wire in the circuit?

  By moving the crocodile clips further apart
• What does a straight line graph passing through zero indicate about resistance and wire length?

  The resistance of the wire is directly proportional to the length
• Why is zero error considered a systematic error?

  It cannot be reduced by carrying out repeats
• What is a zero error in the context of this practical investigation?

  A reading on a measuring instrument when the value should be zero
• What causes zero error in this experiment?

  Difficulty in positioning the crocodile clip and resistance at the contact point
• How should you adjust your readings to account for zero error?

  By subtracting the zero error from all of your readings
• How does heating affect the resistance of the wire?

  If the temperature of the wire increases, the resistance will also increase
• What can be done to reduce heating effects during the experiment?

  Use a low potential difference and turn off the current between readings
• How does a variable resistor work?

  • Contains a long piece of wire in a coil
  • The slider changes the length of the wire the current runs through
  • Used to control the potential difference across a component
• How does increasing resistance affect the brightness of a lamp in a circuit?

  It makes the lamp dimmer
• Where can you find more questions on required practicals?

  In the vision workbook
• What should you be able to do by the end of the video?

  Describe how to investigate the factors affecting the resistance of electrical circuits