Resistance of a Filament

• Why are resistors used in circuits?

  To control the potential difference across components
• What is the symbol for a resistor?

  A zigzag line
• What happens when you change the potential difference across a resistor?

  You can measure the current flowing through it
• What does the graph of current versus potential difference look like for a resistor?

  The current is directly proportional to potential difference
• What do we call resistors that have constant resistance?

  Ohmic conductors
• Under what condition does the ohmic behavior of resistors apply?

  If the temperature does not change
• What experiment is conducted with a filament lamp?

  Changing potential difference and measuring current
• How does the current through a filament lamp compare to that of a resistor?

  It is not directly proportional to potential difference
• Why does the resistance of a filament lamp increase at high temperatures?

  Atoms vibrate more, causing more collisions
• What does the graph of a filament lamp indicate about resistance?

  Resistance increases as potential difference increases
• What is a key characteristic of a filament lamp?

  It is not an ohmic conductor
• What is the shape of the current potential difference graph for a filament lamp?

  • Non-linear curve
  • Current increases at a decreasing rate
  • Indicates increasing resistance with temperature
• What are the key features of filament lamps?

  • Filament is a fine wire
  • Produces light when heated
  • Commonly used in homes
  • Being phased out for energy efficiency
• What are the differences between ohmic and non-ohmic conductors?

  Ohmic conductors:

  • Constant resistance
  • Current directly proportional to voltage

  
  

  Non-ohmic conductors:

  • Resistance changes with temperature
  • Current not directly proportional to voltage
• What happens to the filament in a lamp when current passes through it?

  • The filament gets extremely hot
  • Causes the filament to glow
  • Produces light as a result