Electric Current (HL IB Physics)

• Electric current is the rate of flow of charge carriers and is measured in units of amperes (A) or amps
• Charge can be either positive or negative and is measured in units coulombs (C)
• When two oppositely charged conductors are connected together (by a length of wire)
  • The charge will flow between the two conductors, giving rise to a current
  • The greater the flow of charge, the greater the electric current

Charge can flow between two conductors. The direction of conventional current in metal is from positive to negative

• In electrical wires, the current is a flow of electrons
• Electrons are negatively charged so they flow away from the negative terminal of a cell towards the positive terminal
• Conventional current is defined as the flow of positive charge from the positive terminal of a cell to the negative terminal
  • This is the opposite of the direction of electron flow, as the conventional current was described before the electric current was really understood 

Direct current flows from the positive to the negative terminal of the battery in a circuit. Electrons flow in the opposite direction

• The potential difference in the circuit causes the current to flow

• Current is measured using an ammeter

• Direct current (dc) flows through the circuit in one direction  
  • The direction of conventional current is from the positive terminal to the negative one 
  • This is opposite to the electrons flow
• Direct current is produced when from cells and batteries 
  

Direct current is current that only flows in one direction and has one value

• The equation for current is:

• Where: 
  • I = current (A)
  • Δq = change in charge (C)
  • Δt = time interval (s)