transformers

• What does a basic transformer consist of?

  a primary coil and a secondary coil wound on an iron core
• Why is iron normally used in a transformer?

  it is easily magnetised
• What is equation linking voltage at the primary coil, number of turns on the primary coil, voltage at the secondary coil, and number of turns on the secondary coil?

  
• What are the units for voltage at the primary coil and voltage at the secondary coil?

  V or volts
• What is equation linking voltage at the secondary coil, current at the secondary coil, voltage the primary coil, current at the primary coil?

  Vs × Is = Vp × Ip
• In a step-up transformer is Vs greater than, less than or equal to Vp?

  Greater than
• In a step-down transformer is Vs greater than, less than or equal to Vp?

  less than
• What is Vs × Is?

  the power output in the secondary coil
• What is Vp × Ip?

  the power input in the primary coil
• What are the units of power?

  W or watts
• Why is a step up transformer used in the national grid?

  to increase the volatage which in turn decreases the current therefore makes the process more energy efficient as less thermal energy is transferred to the surroundings
• Why is a step down transformer used in the national grid?

  to reduce the voltage to a safe level for consumers to use