Resistance and I-V Characteristics

• What is resistance in a circuit?

  Resistance is how much a component slows down the flow of current.
• How is resistance related to current and potential difference?

  Resistance is related to the size of the current and potential difference.
• What unit is resistance measured in?

  Resistance is measured in ohms, Ω.
• What factors can affect the resistance of a circuit?

  The resistance can depend on whether components are in series or parallel and the length of a wire.
• How can you investigate how the length of a wire affects resistance?

  • Use a circuit to measure resistance.
  • Attach a crocodile clip to the wire at the 0 cm position.
  • Change the length of the wire and measure the resistance.
• What do I-V characteristics represent?

  1. V characteristics show how the current varies as you change the potential difference across a component.
• What are ohmic conductors?

  Ohmic conductors are components with constant resistance.
• What is the shape of the I-V characteristic for ohmic conductors?

  The I-V characteristic for ohmic conductors is a straight line.
• How can you calculate resistance from an I-V characteristic?

  You can calculate resistance using the formula \( R = \frac{V}{I} \).
• What steps are involved in constructing an I-V characteristic for a component?

  1. Vary the resistance of the variable resistor.
  2. Record the potential difference across the component for each current value.
  3. Repeat readings to get an average.
  4. Reverse the current direction and measure again.
  5. Plot a graph of current against potential difference.
• What happens to the current through an ohmic conductor at constant temperature?

  The current is directly proportional to the potential difference.
• What is a filament lamp's I-V characteristic shape?

  A filament lamp has a curved I-V characteristic because the resistance changes.
• What is a diode's function in a circuit?

  A diode only lets current pass through it in one direction.
• How does the resistance of a diode change with current direction?

  The resistance of a diode depends on the direction of the current.
• What precaution should be taken when investigating the I-V characteristic of a diode?

  A protective resistor should be added to the circuit to prevent high current.
• What type of ammeter should be used when measuring current through a diode?

  A milliammeter should be used to keep the current low.
• What is the equation linking resistance, potential difference, and current?

  The equation is \( R = \frac{V}{I} \).