The National Grid

What is the definition of the National Grid?

• The power generation apparatus.

• The flow of current around a house.

• A network of cables and transformers.

• A big grid in the road.

When electricity is transported from power stations to our homes in what way do we change it for transport?

• Increase the voltage.

• Increase the current.

• Increase power.

• None of the above.

For what reason do we increase the voltage in the power lines?

• To increase the amount of heat produced.

• To maximise the intensity of power modulation frequency.

• To reduce the amount of birds killed.

• To reduce energy losses.

In what form is energy lost when the electricity is transported?

• Eddy currents causing electrons to be lost to Earth.

• Thermal energy to the wires and dissipated in the air.

• Interference with radio signals.

What is a step up transformer?

• Increases the voltage and the current.

• Increases the voltage and decreases the current.

• Increases the current and decrease the voltage.

• Decreases both the current and the voltage.

• Increases the voltage only.

What is a step Down transformer?

• Increases the voltage and the current.

• Increases the voltage and decreases the current.

• Increases the current and decrease the voltage.

• Decreases both the current and the voltage.

• Increases the voltage only.

What is a laminated iron core?

• An orb at the centre of the Earth.

• A nuclear reactor that generates power.

• An iron core coated with a thick layer of plastic to insulate it.

• Medium through which a magnetic field is generated and generates a current.

In the primary coil of a transformer I have a voltage of 25,000V. There are 10 turns on the primary coil and 160 turns on the secondary coil. Assume the transformer to be 100% efficient. What is the voltage in the secondary coil?

• 1563V

• 400,000V

• 230V

• 75,000V