Current

• What is the definition of current?

  Flow of electrical charge
• What is the unit of current?

  Ampere, A
• What is the definition of potential difference?

  Driving force that pushes charge round
• What is the unit of potential difference?

  Volt, V
• What is the definition of resistance?

  Anything that slows down charge flow
• What is the unit of resistance?

  Ohm, Ω
• What happens when there is no source of potential difference in a circuit?

  No current flows
• What happens when there is a source of potential difference, like a battery?

  Current flows
• What factors affect current through a component?

  1. The component’s resistance:

  • Greater resistance = smaller current

  1. The potential difference across the component:

  • Greater potential difference = larger current (for fixed resistance)
• What is the formula for charge flow in a circuit?

  Q = It
• What does the variable Q represent in the formula Q = It?

  Charge flow in coulombs, C
• What does the variable I represent in the formula Q = It?

  Current in amperes, A
• What does the variable t represent in the formula Q = It?

  Time in seconds, s
• How is the size of the current related to the rate of flow of charge?

  Size of current = rate of flow of charge
• What is the relationship between current and resistance?

  Greater resistance results in smaller current
• What is the relationship between potential difference and current?

  Greater potential difference results in larger current
• How do current, potential difference, and resistance interrelate in a circuit?

  Current depends on potential difference and resistance