Resistors

• What is a resistor?

  A component that resists electric current
• What is the symbol for a resistor?

  A zigzag line
• What does the current potential difference graph for an ohmic conductor show?

  Current is directly proportional to potential difference
• What happens to electrons in a conductor?

  They collide with atoms, transferring energy
• What does resistance indicate in a circuit?

  The potential difference needed to drive current
• How is resistance calculated?

  Resistance = potential difference / current
• What is the unit of resistance?

  Ohm
• Why might resistance be considered useful in a circuit?

  It can control the brightness of components
• How can you make a lamp dimmer in a circuit?

  Add extra resistance or lower potential difference
• What happens to the potential difference when a resistor is added in series?

  It is shared between the lamp and resistor
• If a resistor has a potential difference of 10 volts and a current of 0.1 amps, what is its resistance?

  100 ohms
• What does a straight line through zero on a current-potential difference graph indicate?

  Current is directly proportional to potential difference
• When does the resistance of an ohmic conductor remain constant?

  When the temperature is constant
• What is an ohmic conductor?

  A resistor with constant resistance
• What are the key points about resistors?

  • Resistors limit current flow
  • They have a specific symbol
  • Resistance is calculated as $R =$$\frac{V}{I}$
  • Resistance is measured in ohms
  • Useful for controlling brightness in circuits
• What is the relationship between current and potential difference in an ohmic conductor?

  • Directly proportional relationship
  • Graph shows a straight line through zero
  • Resistance remains constant at constant temperature