Generation Of Electricity Flashcards
Explain the conduction of electricity in metals.
Where metals are pictured as crystals with a framework of fixed ions and free electrons.
Explain the conduction of electricity in semi conductors.
Semiconductors are pictured as a framework of fixed atoms joined by covalent bonds. These covalent bonds allow some conduction when they contain extra electrons, or spaces where electrons should be (known as holes). Holes behave as positive charges. As electrons shuffle from one covalent bond to the next to fill the hole, the hole effectively moves the other way.
Explain a semi conductors rate of conduction.
A semiconductor’s conductivity depends on the rate at which the crystal bonds are broken. The breaking of bonds releases an electron and a hole. The rate at which this occurs depends on the rate of vibration of the atoms – i.e., on the amount of thermal energy stored in the material.
Explain how light energy increases conduction in semi conductors.
Energy input, such as that from light, increases the vibration of the atoms and therefore increases the conductivity of semiconductors.
What is a N type semiconductor?
We can create semiconductors that tend to produce either more electrons (negative or n-type)
What is a P type Semiconductor?
A semi conductor created to make more holes (positive or p-type).
How is a photovoltaic cell created?
A photovoltaic cell (solar cell) is made by placing a thin slice of n-type silicon over a thicker slice of p-type silicon. When light falls upon the region where they meet, called the p-n junction, both electrons and holes flow across the junction and an Electromotive Force (EMF) is generated.
How is a photovoltaic cell connected to a circuit?
Strips of metal on the top and bottom surfaces of the photovoltaic cell act as terminals which may be connected to an external circuit, providing a source of electrical power.
How can the charge from a piezo crystal be connected to a circuit?
The charges are collected using certain materials, e.g., aluminum foil across the surfaces of the crystal, to form terminals.
What using electromagnetic induction, how can you increase the induced voltage?
The induced voltage increases in proportion to the magnetic field strength, the movement speed, and the effective length of the conductor.
