Req Pratical: Resistance

• What factors are being investigated in the practical?

  • Factors affecting resistance
  • Focus on the length of a wire
• What equipment is used in the practical?

  Battery, ammeter, voltmeter, wire
• What does the ammeter measure in the circuit?

  Current
• What does the voltmeter measure across the wire?

  Potential difference
• How do you calculate resistance in the circuit?

  Resistance = Voltage / Current
• What is the relationship between resistance and the length of the wire?

  Resistance is directly proportional to length
• How can you increase the length of the wire in the circuit?

  Move the crocodile clips further apart
• What does a straight line graph through zero indicate?

  • Resistance is directly proportional to length
  • Indicates a linear relationship
• What is a zero error in measuring instruments?

  A reading when the value should be zero
• Why is zero error considered a systematic error?

  It cannot be reduced by repeating measurements
• How should you adjust readings to account for zero error?

  Subtract the zero error from all readings
• What causes zero error in this practical?

  Contact resistance and crocodile clip positioning
• How does heating affect resistance in the wire?

  Increased temperature raises resistance
• What can be done to reduce heating effects in the wire?

  Use a low potential difference
• When should the current be turned on during the experiment?

  Only when taking a reading
• How does a variable resistor work?

  • Contains a long piece of wire in a coil
  • Slider changes the length of wire in the circuit
• How does increasing resistance affect the brightness of a lamp?

  Makes the lamp dimmer
• What is the main focus of this practical investigation?

  Factors affecting resistance in circuits