electricity p2

• What is required for an electrical appliance to work?

  A supply of electricity
• Name two examples of electrical appliances.

  TV and iron
• How does the National Grid supply electricity to homes?

  It connects power stations to various locations
• What is the potential difference of electricity supplied to homes in the UK?

  230 V a.c.
• What is the frequency of electricity supplied to homes in the UK?

  50 Hz
• What type of current is supplied to homes in the UK?

  Alternating current (AC)
• What is the difference between alternating current (AC) and direct current (DC)?

  AC changes direction; DC flows one way
• Why is alternating current (AC) more efficient for long distances?

  It allows for higher voltage transmission
• What is the role of transformers in electricity supply?

  To change voltages for efficient transfer
• What are the two types of transformers and their functions?

  • Step-Up Transformer: Increases potential difference, decreases current
  • Step-Down Transformer: Decreases potential difference, increases current
• What is the formula for calculating power in an electrical circuit?

  Power (W) = Current (A) x Voltage (V)
• What is the power output of a power station with a primary coil of 250,000,000 W?

  250,000,000 W
• If the primary coil has a current of 12 A and a potential difference of 45 V, what is the power output?

  540 W
• What is the purpose of a fuse in an electrical plug?

  To stop the appliance if current is too high
• Why does an appliance stop working when the fuse melts?

  It creates a gap in the circuit
• What happens if a 5 A fuse is used in a kettle that requires a 13 A fuse?

  The kettle would not work
• How is power defined in electrical appliances?

  • Power = Energy transferred per second
  • Measured in watts (W)
  • Formula: P = E / t
• Calculate the power of a kettle with a potential difference of 230 V and a current of 10.5 A.

  P = 2415 W
• What is the power of a light bulb with a resistance of 0.5 ohms and a current of 4 A?

  P = 8 W
• Calculate the energy transferred by a 1500 W hairdryer used for 180 seconds.

  E = 270,000 J