Electricity Unit Test Flashcards
What is an ammeter?
An ammeter measures amps or amperes which is a measure of current (I). An ammeter has to be connected in series to measure amps and current.
What is an ampere?
an ampere is how current electricity is measured. ex. 12 amps Amperes are measured on an ammeter
What is charging by contact?
Charging by contact is when you rub 2 objects together and allow the electrons to move from one object to the other. This leaves one object positive (because it has lost electrons and therefore has more protons than electrons) and one left negative (because it has gained electrons and therefore has more electrons then protons)
What is the difference between charging by contact and charging by induction?
Charging by contact occurs when you rub 2 objects together and the electrons are transferred from one object to the other. Charging by induction occurs when a charged object is held near a neutral object and either attracts or repels the electrons creating a charge that is “induced” or left behind. ex. if a negatively charged object is held near a neutral object, the negative object’s electrons repels the electrons in the neutral objects and leaves behind a positive charge in that end of the object.
What is a circuit breaker?
A circuit breaker is like a safety device that prevents the cables and wires in your home from overheating and catching fire.
How does a circuit breaker work?
It works by the thermal expansion of metal like Christmas lights. A spring is held closed by a metal pin and when the pin gets hot it changes shape and allows the spring to push open the circuit stopping the flow of electricity.
What is a circuit diagram?
A diagram of how a circuit flows. It uses symbols to represent each component and is always a complete or closed circuit. This is an easy way to tell if a circuit is in series or parallel.
What is a coal powered generating station?
It is a form of generating energy by burning coal to create heat to cause steam to rise.
How does a coal powered generation station work?
Coal is burned underneath water. this causes the water to heat up enough so that it ca change state into steam. The steam is hot so it rises and causes a wheel to turn which contains the magnet in the coil of wire and allows it to turn creating electricity.
What is conductivity?
The ability of materials to move freely to, from and within an object. Objects that allow electrons to move easily are called conductors
What are examples of a conductor?
Metals (copper, silver.gold)
What are fair conductors? Examples?
Fair conductors allow electricity to pass through with difficulty ex. Human body, salty water (the more salt, the more conductive), moist air, soil.
What is current electricity?
The motion of electrons through a circuit. The electrons can be made to move by either turning a magnet in a coil of wire (generator) or by chemical reactions (like a battery). A circuit has to be complete or closed for electrons to be able to move.
What is an electric current or current?
The number of electrons that flow. It is measured in amps or amperes on an ammeter that has to be connected in series in a circuit. It is represented by the letter I.
What is an electrical circuit?
It is the path that electrons can flow. It includes a power source, a load and conducting wires (electrical wires). A circuit has to be closed for electrons to flow. Each circuit has a measure of voltage (volts), current (amps) and power (watts).
What is electrical discharge?
It is the way that an object can lose its electric charge. This can either occur by contact with another object or grounding which allows electrons to flow in or out of an object to balance protons and electrons or you can discharge an object by a spark which is where electrons “jump” from one object to another due to a build up of charge.
What is an electrical load?
Converts electrical energy into any other form of energy. Ex. a light bulb converts electrical energy into light and heat
What is electron affinity?
An objects desire for electrons. The triboelectric series orders materials based on their tendency to gain or lose electrons. An object with high electron affinity tends to gain electrons where as an object with a low electron affinity tends to lose electrons.
What is an electroscope?
It is an instrument that can detect an electric charge by showing the leaves of the electroscope spreading apart.
How does an electroscope work?
A charge is induced in the head of the electroscope. Based on the charge of the object, the electrons will either be attracted to the objects leaving only protons in the leaves causing the leaves to spread apart (because 2 of the same charges repel) or the electrons will be repelled by the object causing both leaves to be negatively charged and spread apart.
What is friction?
The force resisting the relative motion of 2 surfaces in contact. Ex. rubbing 2 things together.
How does friction create electric charges?
Friction can be used to transfer electrons from one object to another. The force of the friction can be strong enough to allow electrons to be removed from one object and transferred to another. Some objects lose electrons more easily than others.
What is a fuse?
It is like a circuit breaker and acts like a safety device that prevents circuits from overheating and catching fire due to a circuit going over it’s maximum current.
How does a fuse work?
A fuse melts below the circuits maximum current. The issue is that if the wrong fuse is put in, too much current could go through the circuit and cause the wires to heat up and catch fire.
