# Generating electricity

Flashcards by annjb2898, updated more than 1 year ago
 Created by annjb2898 almost 7 years ago
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### Description

GCSE Science Year 10 Flashcards on Generating electricity, created by annjb2898 on 05/28/2014.

## Resource summary

 Question Answer How can the current from a dynamo can be increased? Give three ways. The current from a dynamo can be increased by: - using a stronger magnet - increasing the number of turns on the coil - rotating the magnet faster. What can the output from a dynamo be displayed on? The output from a dynamo can be displayed on an oscilloscope. What does an oscilloscope trace show? An oscilloscope trace shows how the current produces by the dynamo varies with time. What is the time for one complete cycle called? The time for one complete cycle is called the period of the alternating current. What is the height of the wave on a oscilloscope trace? The height of the wave is the maximum (peak) voltage. What the length of the wave on a oscilloscope represent? The length of the wave represents the time for one cycle. What is the equation for frequency using period? Frequency = 1 ÷ period What is frequency measured in? Frequency is measured in hertz (Hz). What is period measured in? Period is measured in seconds (s). What does a simple generator consist of? A simple generator consists of a coil of wire rotating between the poles of a magnet. How is a current produced by a simple generator? - The coil cuts through the magnetic field as it spins. - A current is produced in the coil. How else can a current be produced? A current can be produced if the coil remains stationary and the magnets move. How do generators at power stations work? Generators at power stations work on the same principle. How does a turbine drive a generator in a conventional power station? In conventional power stations, fuels are used to heat water: - water boils to produce steam - steam at high pressure turns a turbine - the turbine drives a generator. How is efficiency a measure of? Efficiency is a measure of how well a device transfers energy. How is energy in a power station lost? Energy in a power station is lost in the boilers, generators and cooling towers. What is the equation for efficiency? efficiency = useful energy output / total energy input PRACTICE QUESTION What is the efficiency of a power station if 60MJ of fuel energy is converted into 20MJ of electrical energy? efficiency = useful energy output / total energy input efficiency = 20000000 / 60000000 efficiency = 0.33 or 33 %

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