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Is there an Ultimate Energy Source? Is there an ultimate energy source? The Sun is the ultimate energy source The grass gets its energy from the Sun via photosynthesis. The lamb gets its energy by eating the grass …. …. and WE get our energy by eating the lamb! Forms of Energy Gravitational Potential Energy This is energy when something is ‘out of position’. This rock climber has potential energy. The further she climbs – the more potential energy she would gain. Water held behind a dam has this type of energy too. Chemical Potential Energy When a fuel burns, its energy is released by chemical reactions. The energy stored in the fuel is called chemical potential energy (or chemical energy for short). Batteries also store chemical potential energy. Kinetic Energy This is energy due to motion. All moving objects have kinetic energy The faster they move (or the more mass they have) the more kinetic energy they have Elastic Potential Energy A stretched rubber band can do work when released. It has elastic potential energy Electrical Energy In circuits, the current is a flow of tiny charged particles called electrons. Electrons can transfer energy, for example from a circuit to a hairdryer. They have electrical energy. Nuclear Energy An atom has a nucleus at its centre. This is made up of particles, held by strong forces. In some atoms the particles become rearranged or the nucleus splits and energy is released. Thermal Energy When hot objects cool down, their atoms and molecules slow down and lose energy. This is known as thermal energy or heat. Radiated Energy Examples of this are light from a lamp and radio signals from a transmitter. Sound Anything that makes a noise has this form of energy. For example air compressions from a loudspeaker or other sound source. Energy Transfers What is the energy conversion in each of the solar cells? Light (radiated) Electrical Energy What are the energy transfers in this match? Chemical Energy Light & Heat Sound is wasted What energy conversions happen in a windmill? Kinetic Energy Electrical Energy What is the unit for ENERGY? The Unit for all forms of energy is the Joule (J). The unit is named after the scientist in the picture. 1 kJ = 1,000J 1 MJ = 1,000,000J Conservation of Energy & Efficiency What is the Principle of ‘Conservation of Energy’? ENERGY can never be CREATED or DESTROYED – it can only be CONVERTED from one form to another. Another important principle is: Energy is ONLY USEFUL when it is CONVERTED from one form to another. ‘Energy cannot be created or destroyed, but it can be changed from one form to another’ Chemical Energy Light (radiated) Energy wanted Heat (thermal) Energy wasted The wasted Heat Energy now heats up the surroundings. It is NEVER destroyed! Are energy conversions 100% efficient? NO device is 100% efficient and the wasted energy is dissipated usually as HEAT & SOUND Think of this washing machine. It gets noisy and hot when it is switched on to wash our clothes What is EFFICIENCY? The efficiency of any device is defined as: Efficiency = Useful energy OUTPUT Useful energy INPUT Energy out Efficiency x Energy In Efficiency can be expressed as a fraction, decimal or percentage Calculate the efficiency of this computer 1200J of electrical energy is supplied to the computer. 200J of energy are wasted in the form of heat & sound. Efficiency = Energy output Energy Input = 1,000 / 1,200 = 0.83 (or 83%)