For example, we have chemical energy in the form of fuels and can convert that chemical energy into electricity. How does that process work? How can we turn kinetic energy of wind mills to electricity? How does sunlight turn into heat energy? How come we can measure energy in Joules when there are so many forms of it?
In: Chemistry
How can we measure energy? Most measurements measure the relevant energy and not the “total” energy content. Energy cannot be measured directly but it is possible to calculate the energy that was converted based on the relevant effects. For example, it is possible to measure the rise in temperature of a fixed amount of water to determine how much energy was used to heat it up. The precision of this measure depends on the nature of the experiment and devices used. Experimental physics isn’t about “absolutely true and 100% accurate” measures, it is about what is “good enough” for that application. For example, if measuring heat output, calculating the bonding energy between neutrons and protons is irrelevant if the amount that this energy contributes to the experiment is negligible.
Conversion of energy is about releasing or storing energy in certain states. For example a water pump moving water from the ground to an overhead tank converts electrical energy to motion of the pump which is then converted to kinetic energy of water movement and then to gravitational potential energy of that mass of water suspended above the ground. A battery stores energy by converting electrical energy to the energy of chemical bonds and when the battery is discharged, the chemical bond energy is converted to electrical energy.
A windmill to a wind turbine converts the motion of wind to the rotational motion, this rotation is applied to the coils within the generator. These coils are suspended in magnetic fields. A moving coil in a magnetic field induces electrical potential and in a suitable circuit, this causes electrons to flow. This flow of electrons is the electrical current which can be transmitted through wires to do stuff which is where the energy is released or used.
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