Electricity | Year 9 Physics (Cambridge) PDF Download

Voltage and Resistance

• Voltage (V)
  • Voltage is the electric potential difference between two points in a circuit.
  • It is measured in volts (V) using a voltmeter.
  • Example: A battery provides 1.5V to power a small light bulb.
• Resistance (R)
  • Resistance opposes the flow of electric current.
  • It is measured in ohms (Ω) using an ohmmeter.
  • Example: A resistor with 100Ω resistance limits the current in a circuit.

Measuring Current and Voltage in Series Circuits

• Series Circuits
  • Components are connected in a single path.
  • Current (I) is the same through all components.
  • Example: In a series circuit with a 12V battery, each component gets the same current.
• Measuring Current
  • Current is measured in amperes (A) using an ammeter.
  • Example: An ammeter shows 0.5A flowing through a series circuit.
• Measuring Voltage
  • Voltage across each component adds up to the total supply voltage.
  • Example: Voltmeter readings show 6V across each resistor in a series circuit with two 6V resistors.

Measuring Current and Voltage in Parallel Circuits

• Parallel Circuits
  • Components are connected in multiple paths.
  • Voltage (V) is the same across all components.
  • Example: Different appliances in a house are connected in parallel to a 220V supply.
• Measuring Current
  • Total current is the sum of currents through each branch.
  • Example: Ammeter readings show 2A through one branch and 3A through another in a parallel circuit.
• Measuring Voltage
  • Voltage across each branch is equal to the supply voltage.
  • Example: Voltmeter readings indicate 12V across each branch of a 12V parallel circuit.

Summary

Electricity involves understanding voltage, resistance, and how current behaves in series and parallel circuits. Voltage is the potential difference that drives current through resistances, which oppose the flow. In series circuits, components share the same current, while in parallel circuits, components share the same voltage. These principles help in designing and understanding electrical circuits for various applications.