Lecture 4.1c

Which form of energy is mainly used to do work?

• Solar energy

• Wind energy

• Electricity

• Biofuel

How is electrical energy conventionally produced via steam turbines?

• By using solar panels to generate electricity directly

• By combusting fossil fuels to release energy

• By using wind turbines to generate electricity

• By using hydroelectric dams to generate electricity

What is the role of steam in the production of electrical energy using steam turbines?

• To cool down the turbine

• To provide lubrication to the turbine

• To move over a turbine, passing on kinetic energy to make it spin

• To condense into water and generate electricity

What happens to the water in the boiler during the energy production process in steam turbines?

• It is cooled down to form ice

• It is converted into steam

• It is used to lubricate the turbine

• It is used to generate combustion gases

What is the final form of energy produced by the steam turbine system?

• Mechanical energy

• Thermal energy

• Electrical energy

• Chemical energy

What are photovoltaic cells more commonly known as?

• Wind turbines

• Solar cells

• Hydroelectric cells

• Geothermal cells

What type of energy do photovoltaic cells transform into electrical energy?

• Mechanical energy

• Chemical energy

• Electromagnetic energy

• Thermal energy

Where can photovoltaic cells commonly be seen?

• On many domestic and industrial buildings

• In underground mines

• On the ocean floor

• Inside nuclear reactors

What is the role of photons in light in the operation of photovoltaic cells?

• They transfer energy to electrons in the semiconductor.

• They cool down the semiconductor.

• They produce greenhouse gases.

• They absorb electrons from the semiconductor.

What happens to electrons in the semiconductor when they absorb energy from photons?

• They transition to a lower energy state.

• They transition to an excited state and produce a current.

• They remain in the same state.

• They are emitted as light.