Physics sharpening Flashcards
What is geothermal energy?
Thermal energy generated and stored in the earths crust. Can be used for heat or electricity. Using for heat is cheaper as the water is pumped into the ground, warmed up and pumped back to the surface to heat our homes. For electricity, the water is pumped down and kept there for so long that it turns to steam. When the steam rises, the gas turns turbines and generates electricity. Geothermal power can only be used in certain places such as volcanic regions and power plants can be expensive to build. However running it doesnt produce any pollutants and is a renewable resource
What are biofuels?
Fuels that are made from recently living organisms. Generally come from plants or algae. Although burning biofuels release carbon dioxide, it is seen as carbon neutral as they took up that carbon dioxide whilst growing. They are also renewable, cheap to make and easy to transport. However somewhere is needed to grow these plants which could lead to deforestation and energy is needed to harvest and transport.
What is hydroelectricity?
This is when a big dam prevents water from flowing like it should, creating a much higher water level on one side than the other. Water coming from upstream is trapped and creates a reservoir. The difference in water level is used to generate electricity as the stored water has huge amounts of gravitational energy. The force of the water passing through the dams turns a turbine which is connected to a generator. Large amounts of energy with no pollution and are reliable sources of energy. However, areas can get flooded and the set up is expensive
What is a tidal barrage?
This is when a big dam prevents water from flowing like it should, creating a much higher water level on one side than the other. Tides are made use of as twice a day there is a high tide which is trapped so when the tide falls, there’s more water on one side than the other. The difference in water level is used to generate electricity as the stored water has huge amounts of gravitational energy. The force of the water passing through the dams turns a turbine which is connected to a generator. Large amounts of energy with no pollution and are reliable sources of energy. However there is an impact on surrounding areas and it is expensive to set up.
AC/DC current
In an alternating current, the direction of the current is constantly changing. It is often used when we use an alternating potential difference (one that fluctuates between positive and negative). The UK mains supply (plug sockets) is AC- 50 hertz and 240 volts. Direct currents direction is constant and produces by a direct potential difference (positive or negative the entire time). It is found in cells or batteries. Oscilloscopes display the graphs on a monitor.
What is internal energy
The total energy stored by the particles making up a substance or system. It is made up of 2 parts. The kinetic energy stores is the movement energy of the particles. The more internal energy that a substance has, the higher the temperature is. However some materials require a lot more energy to increase their temperature.
What is specific heat capacity?
The amount of energy needed to raise the temperature of 1kg of a substance by 1oc
Internal energy formula
Change in internal energy=mass x specific heat capacity x temperature change
What is specific latent?
The energy required to change 1kg of a particular substance from one state to another without changing its temperature. Specific latent heat of vaporisation is the energy change when a substance changes between a liquid and a gas. Specific latent heat of fusion is energy change when a substance changes between a solid and liquid.
