Current, Potential difference and resistance

• Cell


  Circuit symbol
• Battery


  Circuit symbol
• Lamp


  Circuit symbol
• Fuse


  Circuit symbol
• Voltmeter


  Circuit symbol
• Ammeter


  Circuit symbol
• Diode


  Circuit symbol
• Resistor


  Circuit symbol
• Thermistor


  Circuit symbol
• Variable resistor


  Circuit symbol
• LDR (Light Dependent Resistor)


  Circuit symbol
• LED (Light Emitting Diode)


  Circuit symbol
• Electric current


  The flow of electrical charge
• Equation linking charge, current and time

  1. Q = I t

  2. Charge (Coulombs)

  3. Current (Amperes)

  4. Time (Seconds)
• Current is the same at all points in a closed loop
• Factors current in a circuit depends on

  • 1. Potential Difference (V)
  • 2. Resistance (R)
• Equation to calculate potential difference if current and resistance are known

  1. V = I R

  2. Potential Difference (V)

  3. Current (A)

  4. Resistance (Ω)
• Ohmic Conductor


  • A conductor for which current and potential difference are directly proportional
  • Resistance remains constant as current changes
  • Temperature must be constant