Unit 3 Electricity and Magnetism
ion
A charged atom
transformers and electromagnetism
A device that transfers electric current from one circuit or set of circuits to another, by means of electromagnetic induction and usually for the purpose of changing voltage. Most transformers are iron rings with two coils of wire. The current in the wire on the primary side makes an electromagnet. Because the curren alternates, the magnetic field changes. This induces a current in the wire on the secondary side.
resistance
A material's opposition to the flow of electric current.
factors that can affect resistance
A materials composition affects resistance. Some metals such as silver and copper have low resistance and are very good conductors. Other metals such as iron and nickel have higher resistance. Electrical insulators such as plastic have such a high resistance that electric charge cannot flow through it. Other factors that affect the resistance of a wire are thickness, length and temperature. a thin wire has higher resistance than a thicker wire. a long wire has higher resistance than a shorter wire. a hot wire has higher resistance than a cooler wire.
analog signal
A signal having the characteristic of being continuous and changing smoothly over a given range, rather than switching suddenly between certain levels. Examples: The sound from a human voice is because sound waves are continuous, as is our own vision, because we see various shapes and colors in a continuous manner due to light waves. Even a typical kitchen clock having its hands moving continuously can be represented as an analog signal.
how does a solenoid work
A solenoid's magnetic field acts like a bar magnet. The strength of the magnetic field of a solenoid increases as more loops per meter are used.
electron
A subatomic particle that has a negative charge
Neutron
A subatomic particle that has no charge and that is found in the nucleus of an atom
digital signal
A system of discrete states: high or low, on or off, 1 or 0. Examples: digital watch, computer processing.
integrated circuit
A thin slice of silicon that contains many solid-state components.
Basic Structure of a computer
All types of computers follow a same basic logical structure and perform the following five basic operations for converting raw input data into information useful to their users. Basic structure Input Unit: It is the unit for accepting data and instructions from the user. CPU (Central Processing Unit): CPU is considered as the brain of the computer. CPU performs all types of data processing operations. It stores data, intermediate results and instructions(program). It controls the operation of all parts of computer. Output unit: consists of devices with the help of which we get the information from computer. This unit is a link between computer and users. Output devices translate the computer's output into the form understandable by users
distinguish between open and closed circuits.
Any circuit which is not complete is considered an open circuit. A complete circuit which is not performing any actual work can still be a closed circuit. For example, a circuit connected to a dead battery may not perform any work, but it is still a closed circuit. A circuit is considered to be closed when electricity flows from an energy source to the desired endpoint of the circuit. The open status of the circuit doesn't depend on how it became unclosed, so circuits which are manually disconnected and circuits which have blown fuses, faulty wiring or missing components are all considered open circuits.
proton
Atomic particle with a positive electric charge.
compare direct to alternating current, and describe some everyday devices that use each.
Direct Current (DC) - In direct current, charges always flow in the same direction. The electric current generated by batteries is DC. Some everyday devices that use DC are: flashlights, cars, & camera
Earth as giant magnet
Earth's magnetic field is mostly caused by electric currents in the liquid outer core, which is composed of conductive, molten iron. Loops of currents in the constantly moving, liquid iron create magnetic fields. From afar, the Earth looks like a big magnet with a north and south pole like any other magnet.
Be able to distinguish between the two types of electric charge. Know what electric charge is.
Electric charge is the physical property of matter that causes it to experience a force when placed in an electromagnetic field. There are two types of electric charges: positive and negative (commonly carried by protons and electrons respectively).
Computer
Electronic device that receives data, processes data, stores data, and produces a result.
devices that make using electricity safer.
Fuses, circuit breakers, ground fault circuit interrupters
How does direct current differ from alternating current?
In direct current (DC), the electric charge (current) only flows in one direction. Electric charge in alternating current (AC), on the other hand, changes direction periodically. The voltage in AC circuits also periodically reverses because the current changes direction.
properties of magnets and how magnets attract and repel.
Object/material that produces a magnetic field with 2 poles (North and South) which pulls on other ferromagnetic materials and repels other magnets. Similar poles repel. Opposite poles attract. The south pole of a bar magnet suspended by a thread moves toward the north pole. Magnets attract objects made of iron, cobalt and nickel.
How can an object become charged?
Objects become charged when their atoms gain or lose electrons. Three ways that objects can gain or lose electrons are by friction, contact or induction.
describe voltage and resistance and their relationships with current.
Ohm's law defines the relationship between the voltage, current, and resistance in an electric circuit: i = v/r. The current is directly proportional to the voltage and inversely proportional to the resistance.
How does resistance affect electric current
Resistance decreases electrical current per Ohm's law. Ohm's law gives current as a ratio of voltage to resistance: 1 volt flowing through 1 ohm of resistance produces 1 ampere of current.
Be able to describe what makes semiconductors so important to today's electronics.
Some materials behave in between a conductor and an insulator. These materials are called semiconductors. Semiconductors are important in electronics such as computers and mobile phones because their conductivity can be controlled allowing for current to flow in just one direction or only under certain circumstances. The most commonly used semiconductor in electronics today is silicon.
ferromagnetic
Substances that can become magnetized; iron, nickel & cobalt. Their atoms will form magnetic domains.
Basic Functions of a computer
The four basic functions of a computer system are as follows: input output processing storage Input Transferring of information into the system. This may be through a user input device - i.e. keyboard, mouse, scanner etc.. Or though previously loaded software/program, cd etc. Output Output is the exact opposite of input. Output is the function that allows a computer to display information, from the system, for the user. This can be accomplished through the monitor (or other graphical display), printer, speakers etc. Processing This is where the computer actually does the 'work' - manipulating and controlling data over the entire system. Storage Most computers are able to store data both temporarily (in order to process), but also long-term (i.e., permanently). Storage takes place on hard-drives or external storage devices.
Difference between magnetic poles and geographic poles
The geographic north pole marks one end of Earth's axis of rotation. However, this rotation alone is not what causes our magnetic field. Our planet also has deep layers—the inner and outer cores—that spin, and at different rates. The process creates currents and convections in the molten outer core. All of this action generates an effect like a huge electromagnet, creating one magnetic pole in the north and another in the south. They don't correspond to the geographic poles, which are just one visible factor in the whole complex phenomenon. This is why the magnetic poles are not located at the geographic poles and wander constantly—daily, in fact.
What properties of semiconductors make them useful in electronic devises
The property of semiconductors that makes them most useful for constructing electronic devices is that their properties allow them to be used to control the flow of charge.
series circuit
a circuit in which the parts are joined after another such that the current in each part is the same
parallel circuit
a circuit in which the parts are joined in branches such that the voltage across each part is the same.
solenoid
a coil of wire with an electric current in it and therefore produces a magnetic field.
electromagnet
a coil that has a soft iron core and that acts as a magnet when an electric current is in the coil
electric motor
a device that converts electrical energy into mechanical energy
electric generator
a device that converts mechanical energy into electrical energy
transformer
a device that increases or decreases the voltage of alternating current
alternating current and everyday devices that use each
a flow of electric charge that regularly reverses its direction Ex. anything you plug in Low voltage slip rings uses what type of current
electric charge
a fundamental property that leads to the electromagnetic interactions among particles that make up matter
electrical conductore
a material in which charges can move freely
electrical insulator
a material in which charges cannot move freely
magnetic field
a region where a magnetic force can be detected
electric circuit
a set of electrical components connected such that they provide one or more complete paths for the movement of charges
semiconductor
an element or compound that conducts electric current better then an insulator does but not as well as a conductor does
parts of an electrical circuit
an energy source (AC or DC), a conductor (wire), an electrical load (device), and at least one controller (switch).
magnet
any material that attracts iron or materials containing iron
opposite charges
attract each other
static electricity
electric charge at rest, generally produces by friction or induction
resistance
in physical science, the opposition presented to the current by a material or device. Electric charges move more easily through a short wide pathway than through a long narrow one. expressed in ohms
magnetic pole
one of two points, such as the ends of a magnet, that have opposing magnetic qualities
same charges
repel each other
voltage
the amount of work to move a unit electric charge between two points, expressed in volts
magnetic force
the force of attraction or repulsion generated by moving or spinning electric charges
electromagnetism
the interaction between electricity and magnetism
electromagnetic induction
the process of creating a current in a circuit by changing the magnetic field
electric current
the rate at which electric charges pass a given point
electric discharge
the release of electricity stored in a source
