Energy Sources (Cambridge International IGCSE Physics): Exam Questions

Fig. 5.1 shows part of a solar farm. The solar cells tilt and rotate.

The solar farm converts energy from a source into a different, useful form of energy.

State the energy source and the useful form of energy.

Solar farms have advantages and disadvantages.

(i) State two advantages of a solar farm.

(ii) State one disadvantage of a solar farm.

Extract:

Fig. 5.1 shows part of a solar farm. The solar cells tilt and rotate.

Suggest why it is useful that the solar cells can tilt and rotate.

Here are some statements about energy and energy resources.

Some statements are correct. Put a tick (✓) in the box alongside each of these.

square Building hydroelectric power stations has an impact on the environment.

square Burning fossil fuels produces atmospheric pollution.

square Wind turbines are turned using gravitational potential energy.

square Coal and crude oil are sources of renewable energy.

square Geothermal energy is obtained from hot rocks below the ground.

Coal is a non-renewable source of energy.

(i) Explain what is meant by the term non-renewable.

(ii) There are other non-renewable sources of energy.

Place a tick in the box by each non-renewable source of energy.

square nuclear

square oil

square solar

square wave

square wind

State two advantages and two disadvantages of using natural gas as an energy source.

Complete the sentence below about energy sources.

Two methods of using energy from water are ____________ and _____________.

Extract:

Two methods of using energy from water are: Tidal power (turning turbines) / turbines in the sea; Hydroelectric dams;

State two advantages of one of the methods from part (a).

A graph of the energy output of two renewable resources over time is shown in Fig. 1.1. One is a solar cell, the other is a wind turbine.

Fig. 1.1

State which line on the graph represents the energy output of a solar cell.

Extract:

A graph of the energy output of two renewable resources over time is shown in Fig. 1.1. One is a solar cell, the other is a wind turbine.

State which line on the graph represents the energy output of a solar cell.

(c) State which line on the graph represents the energy output of a solar cell:

• Line A; [1 mark]

Explain how you arrived at your answer to part (c).

Define the term "renewable resource".

A list of resources is shown in the table below.

Place a tick in the correct box for each resource.

Extract:

A renewable resource is:

• A resource that can be replenished as it is used / is replaced (by nature) in less than a (human) lifetime; [1 mark]

"A resource that doesn't run out" may or may not gain a mark, depending on the mark scheme for your exam. It is better to use scientific language and refer to rate of use and rate at which the resource is replenished.

Fossil fuels are produced when living matter is compressed. They are continually produced.

Explain why they are not a renewable resource.

Extended tier only

(i) Describe the process of nuclear fusion.

(ii) Explain why nuclear fusion is not currently used as an energy resource.

Fig.4.1 represents a hydroelectric system for generating electrical energy.

Describe how the power station uses the water in the reservoir to generate electricity.

State three advantages of generating electricity using a hydroelectric system compared with using a coal-fired power station.

An electric drill is shown in Fig.4.2.

Complete the sentences about the electric drill. Use words from the box. Each word may be used once, more than once, or not at all.

(i) Energy is transferred electrically from the mains supply to the ............................. store of the drill.

(ii) A second electric drill transfers the same amount of energy per second as the first one. However, it wastes more of this energy.The second drill is less ......................................... than the first drill.[1]

Fig. 5.1 shows a wind turbine.

Describe how the wind turbine produces electricity.

Wind turbines are used in many countries to replace coal-fired power stations.

(i) State one disadvantage of using wind turbines compared to coal-fired power stations.

(ii) State two advantages of using wind turbines instead of coal-fired power stations.

A tidal barrage (dam) produces electricity using tides. Fig. 5.1 shows a diagram of a tidal barrage (simplified).

The water behind the barrage (dam) has most of its energy in one of its energy stores. State the name of this energy store.

Extract:

A tidal barrage (dam) produces electricity using tides. Fig. 5.1 shows a diagram of a tidal barrage (simplified).

The water behind the barrage (dam) has most of its energy in one of its energy stores.

Explain how the tidal barrage (dam) produces electricity.

Fig. 5.1 shows a geothermal power station. It generates electricity.

In a geothermal power station, the process of generating electricity includes seven stages.

Four of the stages are shown below.

P steam turns a turbine

Q hot underground rocks heat the cold water

R the turbine spins a generator

S hot water rises to the surface

The flow chart in Fig. 5.2 shows the seven stages, but it is incomplete. Complete the flow chart by adding the letters P, Q, R and S in the correct sequence.

The cost of electricity obtained from a geothermal power station is similar to the cost of electricity obtained from wind turbines.

Describe one advantage and one disadvantage of using a geothermal power station to generate electricity compared with using wind turbines.

Nuclear fission is used in nuclear power stations to release energy.

Describe how the energy is used to generate electricity.

Describe two environmental problems that arise from using nuclear power stations.

Fig. 4.1 and Fig. 4.2 show two methods of using renewable sources to generate electrical power.

Name the energy source used by each method.

In Fig. 4.1 the energy source is ....................................................

In Fig. 4.2 the energy source is ...................................................

Extract:

In Fig. 4.1 the energy source is: Solar; In Fig. 4.2 the energy source is: Wind;

(i) State two advantages of using the renewable sources in either Fig. 4.1 or Fig. 4.2 for generating electrical power compared to using a coal-fired power station.

(ii) State one disadvantage of using the renewable sources in either Fig. 4.1 or Fig. 4.2 for generating electrical power compared to using a coal-fired power station.

Extended Tier Only

Fig. 3.1 shows solar cells that use radiation from the Sun to generate electrical power.

(i) State the name of the process which releases energy in the Sun.

(ii) Describe what happens in this process.

Apart from solar cells, there are other energy resources used on Earth for which the radiation from the Sun is the main source.

State the name of one of these energy resources and explain whether it is renewable.

State two advantages and two disadvantages of using solar cells to generate electrical power.

Describe how a wind turbine generates electricity from energy in the wind.

Apart from cost, state two advantages of generating electricity using wind turbines compared with using a power station that burns coal.

Apart from cost, state two disadvantages of generating electricity using wind turbines compared with using a power station that burns coal.

Electricity is distributed from wind turbines to homes and industry.

State two disadvantages, apart from cost, of using wind turbines to produce electrical energy for homes and industry.

Energy can be obtained from many different sources.

(i) State two advantages of using solar energy to generate electricity.

(ii) State one disadvantage of using solar energy to generate electricity.

Fossil fuels are also used for electricity generation.

The combustion of fossil fuels produces gases that contribute to the greenhouse effect and acid rain.

(i) State the names of two fossil fuels.

(ii) State the name of one polluting gas that contributes to acid rain.

A city needs a power station that can provide a constant supply of electricity day and night throughout the year.

The city planning committee compares wind energy and nuclear energy for this purpose.

State which one is more suitable and justify your answer.

Extended tier only

A solar panel receives energy from the Sun at a rate of 5.0 kW.

Thermal energy is transferred from the solar panel to water with an efficiency of 20%.

Cold water of mass 15 kg enters the solar panel every hour.

The specific heat capacity of water is 4200 J / (kg°C).

Calculate the temperature increase of the water.

temperature increase = .....................................................°C

State and explain one advantage and one disadvantage of heating the water in a solar panel compared with heating the water in a coal-burning boiler.

Energy sources used to generate electricity are shown in the box.

Which energy sources are non-renewable?

Draw a ring around each energy source that is non-renewable.

The diagram shows a geothermal power station.

Describe how the geothermal power station generates electricity.

Coal and tidal energy are contrasting power sources. (a)

(i) State two environmental disadvantages associated with generating electrical power from coal.

(ii) State one physical advantage that tidal power holds over wind power regarding the reliability of energy generation.

Extended tier only

Fusion is occurring in the centre of a star. The region in which a certain type of fusion is occurring has a diameter of 150 000 km.

Calculate the surface area of this sphere.

Extract:

The region in which a certain type of fusion is occurring has a diameter of 150 000 km. A = 7.1 × 10^16 m^2 (surface area of the sphere)

The weight of the star around the core exerts a large force on the core.

The core experiences a pressure of 26.5 × 10¹⁵ Pa.

(i) Calculate the size of the force due to gravity experienced by the core.

(ii) The volume of the core is approximately constant, so pressure and temperature (in degrees Kelvin) can be approximated as directly proportional. They are related in the following equation:

$P=cT$

c is a constant equal to 2.2 × 10⁹ Pa/K

Calculate the temperature of the core of the star.

Extended tier only

Compare the advantages and disadvantages of nuclear fusion and nuclear fission.

Calculate the number of joules in 1 GWh.

Extended tier only

Tidal power electrically transfers energy in the kinetic store of moving water.

When the tide is moving, a portion of sea water passes through the turbine. The turbine has a cylindrical shape as the turbine spins in a circular path. A turbine is shown in Fig. 1.1.

The cylinder is 24 m long and has a radius of 5.0 m. The tide is travelling at 6.0 m/s.

(i) Calculate the kinetic energy of this cylinder of sea water.

Density of sea water = 1020 kg/m³

(ii) Calculate the time taken for 24 m of water to pass through the turbine at 6.0 m/s.

(iii) Calculate the power transferred to the turbine.

(iv) The turbine's electrical power output is 7.0 MW. Calculate its efficiency.

In America, it is estimated that tidal power would cost $150 per MWh produced, whereas coal only costs $60 per MWh produced.

Suggest why tidal power is more expensive than power from fossil fuels.

Extract:

Tidal power electrically transfers energy in the kinetic store of moving water. When the tide is moving, a portion of sea water passes through the turbine. The turbine has a cylindrical shape as the turbine spins in a circular path. ... The cylinder is 24 m long and has a radius of 5.0 m. The tide is travelling at 6.0 m/s.

Some ocean environmental groups oppose the use of tidal power, stating that it can physically harm aquatic life, as well as impacting their ability to communicate.

Suggest why these statements could be correct.

A coal power station has an average output of 400 MW. Explain how, in a power station, burning a fuel causes a generator to produce an alternating current.

Extended tier only

The Sun has a total power output of 3.8 × 10²⁶ W across its whole surface. The surface of the Earth receives 5.0 × 10⁻⁸ % of this power.

Calculate the total power the surface of the Earth receives from the Sun.

Extract:

The Sun has a total power output of 3.8 × 10^26 W across its whole surface. The surface of the Earth receives 5.0 × 10^−8 % of this power.

Extended tier only

The power that the Earth receives from the Sun is actually twice the percentage given in part (b).

(i) Suggest why the power at the Earth's surface is less than this value.

(ii) The Earth's radius is 6 370 000 m. Calculate the surface area of the Earth which is in sunlight at any one time.

Extract:

Power the Earth's surface receives from the Sun, P_surface = 1.9 × 10^17 W Area of the Earth in sunlight, A_Sun = 2.55 × 10^14 m^2 Power output of coal station, P_coal = 400 MW = 400 × 10^6 W

Extended tier only

(i) Under the assumption that there are no clouds obscuring the Sun, calculate the power that each square metre of the Earth receives from the Sun.

(ii) A solar cell absorbs sunlight over a surface area of 2.5 m². It has an efficiency of 0.6. Calculate its power output.

(iii) Determine the number of solar cells required to match the power output of the coal power station.

Electricity is distributed from wind turbines to homes and industry.

Statements A–F describe the main stages in the transfer of energy from the Sun to electrical energy in a wind turbine generator.

The statements A–F are not in the correct order.

A Air moves from regions of high pressure to regions of low pressure.

B The turbine blades turn a generator.

C Energy from the Sun heats the atmosphere unevenly.

D Uneven heating of the atmosphere produces regions of different atmospheric pressure.

E The generator produces electrical energy.

F Moving air turns the turbine blades.

Complete the flow chart to describe how a wind turbine uses energy from the Sun to generate electrical energy. Insert the missing letters in the empty boxes.