GCSE Science Unit 1 Physics

Process of burning fossil fuels

• Coal is a store of chemical energy.
• When heated it Boils water which is a store of heat energy.
• The water evaporates into steam, which turns turbines.
• A generator converts the kinetic energy in the turbine into Electrical energy.

Disadvantages of Fossil Fuels

• Fossil fuels are non-renewable energy sources. Meaning they will eventually run out.
• Fossil fuels release Carbon Dioxide when they burn. Adding to the greenhouse effect that is causing global warming.
• Coal and oil also release Sulfur Dioxide gas which contributes to acid rain, which damages buildings.

Process of Nuclear Power

• Plutonium and Uranium are highly radioactive elements that are used in the process of Nuclear Fission.
• Nuclear Fission is when the nucleus of an atom is separated into small parts called Nuclei.
• This process releases extremely high amounts of thermal energy, which is used to boil water.
• The steam then turns turbines.
• A generator then turns the kinetic energy of the turbines into electrical energy.

Advantages and Disadvantages

• Much more energy produced per kilo of fuel than any fossil fuel.
• Products of Nuclear are extremely dangerous and need to be stored in a Lead lined container (usually dumped in the sea).
• Nuclear power stations are extremely expensive to build and run. Even closing nuclear power stations is expensive. 

Wind power is a renewable energy source. Meaning it will never run out. When the blades on a wind turbine spin. I generator is converting the kinetic energy from the turbines into electrical energy. A disadvantage of wind power is that when there is no wind, there is no electricity. They are also extremely costly and aren't usually installed for private/home use.

Solar Panels

Solar Panels (or Photo-voltaic cells) are panels that have a chemical in them that turns light into electrical energy.

They are implemented into many machines, like the Parking Ticket Machine below. It can also be installed onto house roofs.

However because the cost of a solar panel is about the same are 20 years worth of electricity bills. You need to own one for 20 years before you start getting free electricity.

Payback Time

This is the time taken to recover from the up-front cost of an appliance.

Suppose you pay £2000 to buy and install a solar panel. You save £100 a year on electricity bills. It would take 20 years of payback time to recover from the £2000 cost of the solar panel.

Conduction

Energy can move through a substance. Metals are good conductors of thermal energy, whereas gases and non-metals are usually poor conductors of thermal energy.

When a metal is heated, ions vibrate around a fixed point. The more heat the more kinetic energy the ions have.

Convection

Convection can only take place in liquids and gases, which are fluids.

When a liquid or gas is heated. When the particles get further apart and less dense, the particles will rise.

When the particles cool down, they become closer together and more dense. Causing them to fall. The process of convection is a continuous cycle.

All objects give out and take in thermal radiation, which is also called infrared radiation. The hotter an object is, the more infrared radiation it emits. Infrared radiation is a type of electromagnetic radiation that involves waves. Because it doesn't involve particles it can even work in space (vacuums).

The colour of a surface can effect the how much infrared radiation the surface will absorb and emit.

Dull Black Matt surfaces are good absorbers of infrared radiation, and therefore its also a good emitter of infrared radiation.

Light Shiny surfaces are poor absorbers of infrared radiation, and therefore its also a poor emitter of infrared radiation.

If you get two objects made of exactly the same materials and painted with the same shape, the thin, flat object will radiate heat faster. This is why radiators are thin, despite the fact that radiators are designed to create convection currents.

Heat is lost through houses in many ways. Below are a few examples of how.

• through the roof
• through windows
• through gaps around doors
• through walls
• through the floor

Thermal Energy is transferred from homes by conduction through walls, the floor, roof and windows. But also by convection currents. When air is heated it the particles will expand and rise up and out through the roof.

Here is how we can reduce heat loss in houses.

• loft insulation will reduce heat loss through the roof
• wall insulation will reduce heat loss through the walls
• curtains and draught excluders will reduce heat loss through windows
• double-glazed windows mean that thermal energy cannot be conducted through the glass because of the thin layer of air in between the two window panes

Magnetic - Energy in magnets and electromagnets

Kinetic - Movement energy

Heat - Also called Thermal Energy

Light - Also called Radiant Energy

Gravitation Potential - Energy stored in raised objects

Chemical - Energy stored in fuel, food and batteries

Sound - Energy released by vibrating objects

Elastic Potential - Energy stored in stretched objects

Electrical - Energy stored in moving or static electrical charges

Nuclear - Energy stored in the nuclei of atoms

An energy transfer is when one form of energy is transferred into another form of energy.

In a simple circuit consisting of a light bulb and battery, chemical energy in the battery is transferred into electrical energy along the wires. Which is then transferred into light energy at the light bulb. There is also waste energy (unwanted forms of energy), in this case it is heat given of by the light bulb.

A Sankey diagram is an accurate way of displaying energy transfer.

Waves are vibrations that transfer energy from place to place without matter (solid, liquid or gas) being transferred. A bit like a Mexican wave!

• Some waves can only be transferred through a medium (a solid, liquid or gas). Seismic waves and Sound Waves are two examples.

• Other waves can travel through a medium, but they do not have to. These are all part of the Electromagnetic spectrum and include Visible Light, Infrared Waves and Microwaves.

Light travels as waves. Waves can be described by their amplitude, wavelength and frequency. The speed of a wave can be calculated from its frequency and wavelength.

• Amplitude is the distance from the peak of a wave to the point of origin. Amplitude is the the loudness of the wave, and is measured in Decibels.
• Wavelength is the distance between one peak and the next. It is measured in millimeters, nanometers or even picometers.
• Frequency is the pitch of a sound. Frequency is how many waves are produced per second. It is measured in Hertz/Hz. The more waves per second, the higher the pitch.

The electromagnetic waves are electric and magnetic disturbances that transfer energy from one place to another.

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wave speed  =  frequency  x  wavelength

        V           =        F         x          λ

      (m/s)               (Hz)                 (m)

This simple word equation can be rearranged to work out the frequency and the wavelength.

F  =  V  /  λ      and      λ  =  V  /  F   

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Transverse Waves

Vibrations are perpendicular to movement.

Longitudinal Waves

Vibrations are along the direction of movement.

Hydroelectric Power Stations (or HEP) use the kinetic energy in flowing water to generate electricity. Water can be flowing through a man-made dam or through natural waterfalls or fast flowing rivers.

Pumped Storage Hydroelectricity is electricity that is generated for peak times. Water stored at low levels is pumped to a higher level. When electricity is in high demand, water is allowed to flow through the turbines to generate electricity.

• The electricity used to operate the pumps is low-cost and off-peak.
• During television adverts there is high demand for electricity because people are putting on the kettle.
• The electricity from the generator is increased through a step-up transformer for traveling along power lines. And decreased through a step-down transformer for use in homes.

Geothermal energy is energy produced from volcanic magma or hot rocks under the earths crust. The hot rocks or magma heat water into steam, this steam then turns turbines. Generators then turn this kinetic energy into electrical energy.

• Geothermal Power stations only exist in places of high volcanic activity. This includes California, Iceland and Italy.
• The steam and hot water is sent up to the surface through pipes.
• Any cold water at the end of the process is pumped back down into the earth, where it will eventually be heated and re-used.

Advantages and Disadvantages

• Geothermal energy is a renewable energy resource and there are no fuel costs.
• No harmful gases or substances are produced in the process.
• Most parts of the world do not have suitable areas where geothermal energy can be exploited.

Renewable Energy

• Renewable energy sources are not in limited supply and will not run out. They include production methods such as Wind Energy, Solar Energy, Tidal Energy, Hydroelectric Energy and Nuclear Power.
• Nuclear power is extremely costly and can cost millions to build, run and destroy a Nuclear power station. It also results in the creation of radioactive substances which are expensive to dispose of.

Non-Renewable Energy

• Non-Renewable energy sources are in limited supply and will eventually run out. They include Coal, Oil and Gas.
• Non-Renewable energy sources usually pollute the atmosphere will harmful gases such as Sulphar Dioxide and Carbon Dioxide.

The National Grid

England, Wales and Scotland is divided into 27 areas. Each area has its own name. Each block has its own electricity transmission system. An electricity transmission system consists of overhead lines and underground cables that carry electricity to buildings.

Transformers

Step-up and step-down transformers are used to increase or decrease electricity.

Power from power stations is stepped-up for traveling along power lines. It is stepped-down for factories and industrial buildings, and stepped-down even more for use in homes.

Specific Heat Capacity

The specific heat capacity of a substance is the energy needed or heat transferred to raise the temperature of 1kg of a substance by 1C.

The unit of specific heat capacity is joules per kilogram per C.

specific heat cap.  =  heat transferred (joules)  /  mass (kg)  x  temp. change (C)

U-Values

This is the energy per second that passes through one square meter of material when the temperature difference across it is 1C.

For example, replacing a single glazed window with a double glazed window that has a U-Value four times smaller then the energy loss will be four times smaller.

Lower U-Value = More Effective the Insulator

Heat Sinks

A heat sink is a component found on most electronic circuit boards that is used to dissipate heat into the surrounding air. A heat sink is usually made of aluminum.

Cooling Fans

A cooling fan is simply a fan installed onto most electrical devices such as computers and TVs. It cools the air inside the machine.