Talha's Physics Academy
Law of Conservation of Energy & Energy Sources
Q.4 State law of conservation of energy. Explain different conversions of energy.
Law of Conservation of Energy
Conversion of Energy from One Form to Another
i. Fossil Fuel Energy
Fossil fuel energy is formed from decayed plants and animals that have been converted to crude oil, coal, natural gases, or heavy oils by exposure to heat and pressure in the Earth's crust over hundreds of millions of years. Fossil fuels store chemical energy, which is released and converted through oxidation (burning). For example, burning charcoal or coal produces heat energy and light energy.
ii. Hydroelectric Energy
Hydroelectricity refers to electricity generated by hydropower using the gravitational potential energy of falling or flowing water. Most hydroelectric power plants use a dam on a river to store water in a reservoir. Water released from the reservoir flows through a turbine, spinning it, which in turn runs a generator to produce electricity.
iii. Solar Energy
The energy radiated from the sun is known as solar energy. Photovoltaic solar panels and solar cells absorb solar energy and convert sun rays directly into electrical energy. Additionally, solar heaters convert solar energy into heat energy to warm water tanks and indoor spaces.
iv. Nuclear Energy
Nuclear energy is released during nuclear reactions such as fission or fusion. Radioactive materials like Uranium and Radium store nuclear energy in their nuclei. A nuclear power plant utilizes this thermal energy to produce steam, which turns a turbine to generate electricity.
v. Geothermal Energy
Geothermal energy is stored deep within the Earth as natural heat in molten rock called magma. Water close to magma converts into steam due to high temperatures, and this thermal energy is brought to the surface to drive electrical generators in geothermal power plants.
vi. Wind Energy
Wind energy is generated by windmills where moving air rotates turbine blades. The kinetic energy of the wind is converted into mechanical power by the turbine, and a generator subsequently converts that mechanical power into electricity. Wind energy is also historically used for sailing ships, pumping water, and grinding grain.
vii. Biomass Energy
Biomass consists of organic material derived from plants, animals, garbage, and agricultural wastes containing stored solar energy. Solid biomass can be burned directly to produce heat, or converted into gas (biogas) and liquid biofuels (such as ethanol and biodiesel).
viii. Tidal Energy
Tidal energy is a form of hydropower that converts energy obtained from ocean tides into electricity. It harnesses the vast movement of water driven daily by the gravitational forces of both the moon and the sun.
Q.5 Differentiate between Renewable and Non-Renewable energy sources.
Renewable Energy Sources
Renewable sources can be replenished naturally and used repeatedly without running out. Examples include solar energy, wind energy, tidal energy, and geothermal energy. Since ancient times, humans have utilized renewable sources such as wind and water power for milling grain and solar radiation for warmth and lighting.
Non-Renewable Sources
Non-renewable resources are finite and will permanently finish once consumed. Coal, petroleum, and natural gases are primary examples. These fossilized energy sources are being consumed at a much faster rate than geological processes can restore them, making them non-renewable.
Comparison Summary
| Feature | Renewable Energy Sources | Non-Renewable Energy Sources |
|---|---|---|
| Availability | Infinite / Naturally replenished continuously. | Finite / Limited supply that depletes over time. |
| Environmental Impact | Generally low emissions and clean energy. | High carbon emissions and pollution upon burning. |
| Examples | Solar, Wind, Hydro, Geothermal, Tidal. | Coal, Petroleum (Oil), Natural Gas, Uranium. |
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