Energy transfer and the national grid

A television converts electrical energy to light energy and sound energy. No unwanted energy is produced.

• True

• False

South Africa has a limited supply of electrical energy.

• True

• False

Choose the correct description for the following word: hydro-electric

• Up and down movement of water creates an air column. Changes in the air column turn the blades of a turbine.

• Blades of the turbine is turned by steam. Steam is produced by a chemical reaction. Mechanical energy is transferred to a generator.

• Blades of the turbine is turned by falling water. Mechanical energy is transferred to a generator.

• Blades turn an axle attached to a gearbox. The gearbox transfers mechanical energy to a generator..

Choose the correct description for the following word: nuclear power

• Blades of the turbine is turned by falling water. Mechanical energy is transferred to a generator.

• Blades turn an axle attached to a gearbox. The gearbox transfers mechanical energy of a turbine.

• Up and down movement of water creates an air column. Changes in the air column turn the blades of a turbine.

• Blades of the turbine is turned by steam. Steam is produced by a chemical reaction. Mechanical energy is transferred to a generator.

Choose the correct description for the following word: wind farm

• Blades turn an axle attached to a gearbox. The gearbox transfers mechanical energy to a generator.

• Up and down movement of water creates an air column. Changes in the air column turn the blades of a turbine.

• Blades of the turbine is turned by falling water. Mechanical energy is transferred to a generator.

• Blades of the turbine is turned by steam. Steam is produced by a chemical reaction. Mechanical energy is transferred to a generator.

Choose the correct description for the following word: tidal power plant

• Blades of the turbine is turned by steam. Steam is produced by a chemical reaction. Mechanical energy is transferred to a generator.

• Blades turn an axle attached to a gearbox. The gearbox transfers mechanical energy to a generator.

• Up and down movement of water creates an air column. Changes in the air column turn the blades of a turbine.

• Blades of the turbine is turned by falling water. Mechanical energy is transferred to a generator.

Which one of the following will NOT reduce the amount of electricity used by a household?

• Cover the electric geyser with a thermal insulator.

• Use the larger plates on the electric stove rather than the smaller ones.

• Wear warm clothing rather than using an electric heater.

• Switch off the light whenever someone leaves a room.

The more efficient an electrical appliance is, the more input energy is converted to (a)   energy.

The input energy of a burning candle is chemical potential energy. The unwanted output energy is (a)   energy.

A generator converts (a)   energy to electrical energy.