20-2-motors-generators-and-transformers_summary

The section discusses the workings of electric motors, generators, and transformers, and how commercial electric power is produced, transmitted, and distributed. Electric motors work by converting electrical energy into mechanical work. They consist of loops of wire in a magnetic field. When current is passed through the loops, the magnetic field exerts a torque on the loops, which rotates a shaft, converting electrical energy into mechanical work. The torque on the loops can be calculated using the equation: 20.12: T = NIABsinθ where T is the torque, N is the number of turns, I is the current, A is the area of the loop, B is the magnetic field, and θ is the angle between the direction of the current and the magnetic field. Generators work by converting mechanical energy into electrical energy. When a coil is rotated within a magnetic field, an emf is induced in the wires of the coil that can be used to power external circuits. The emf induced in the coil can be calculated using the equation: 20.17: emf = πNFAB Sin (ωt) where emf is the induced emf, N is the number of turns, F is the flux density, A is the area of the loop, B is the magnetic field, and ω is the angular velocity of the coil. Transformers are devices that alter the voltage of an AC power supply without changing its frequency. They consist of two coils wound around a magnetic core. The primary coil is connected to the power supply, and the secondary coil is connected to a device that requires a different voltage. The voltage ratio between the primary and secondary coils can be adjusted by changing the number of turns in each coil. Commercial electric power is produced by generating stations, which can be powered by a variety of means such as fossil fuels, nuclear power, or renewable energy sources like wind or solar power. The power is then transmitted over long distances using high-voltage transmission lines, which reduce energy losses by decreasing the current flowing through the lines. The voltage is stepped up at the generating station using a step-up transformer, and stepped down again at the consumer end using a step-down transformer. The standards covered in this section include understanding the relationship between electric and magnetic fields in applications such as generators, motors, and transformers.