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41 Cards in this Set

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Current
The rate at which charge passes a given point. The higher the current is, the more charge passes the point each second.
Unit of Current
the Ampere (A) - amp
Symbol - l
Direct current
DC- a c urrent where the charges always flow in the same direction
Example: Batteries
Alternating current
AC- a current where the charges continually switch from flowing in the reverse direction
Example: current from outlets in your home
Voltage
The difference in energy per unit charge as a charge moves between two points in the path of a current.
Potential difference
Unit of Voltage
Volts (V)
Symbol - V
Electric Circuit
a complete, closed path through which electric charges flow
Load
a device that uses electrical energy
Switch
a device used to open and close a circuit
Types of Circuits
Series and Parallel
Series circuit
a circuit in which all parts are connected in a single loop.
Series Circuit (3 facts)
a. The charges must flow through each part and can only follow one path
b. All the loads share the same current
c. If one load is broken or missing, the other loads will not work.
Parallel circuit
a circuit in which different loads are located on separate branches
Parallel circuit (2 facts)
a. THe loads in parallel circuit do not have th same current in them.
b. If one of the loads is broken or missing, it does not affect the other loads
Ohm's Law
The relationship between current, voltage and resistance
Ohm's Law
Current (A) = _Voltage (V) / Resistance
Electric Power
The rate at which electrical energy is used to do work. Unit of power - watt (W)
Symbol - P
Relationship of Voltage/energy/current
The higher the voltage is, the more energy is released per charge. The current depends on the voltage. The greater the voltage is, the greater the current.
Resistance
The opposition to the flow of electric charge
Unit of resistance - Ohms
Symbol - R
Resistance vs. current
Resistance is like electrical friction- the higher the resistance of a material, the lower the current.
Facts of Resistance (4)
a. An object's resistance depends on the object's material, thickness, length and temperature.
b. The resistance of insulators is so high that electric charges cannot flow in them.
c. Thick and short wires have less resistance
d. The resistance of metals increases as temperature increases.
Electrical Energy
the energy associated with moving charges
Electric current
a continuous flow of charge
Energy
ability to do work
Law of Conservatin of Energy
Energy cannot be created or destroyed, but can be converted from one form to another
Cell
device that produces an electric current by converting chemical energy into electrical energy
Batter
is made of several cells and also converts chemical energy to electrical energy
Electrolyte
a mixture of chemicals that conducs a current in a cell
Electrodes
the part of a cell through which chrages enter or exit - mad eof two different conducting materials that are in contact with the electrolyte.
Friction
Rubbing an object may cause electrons to move between the two objects being rubbed.
Conduction
Electrons are transferred by direct contact.
Induction
Charges in an uncharged object are rearranged without direct contact with a charged object.
Electroscope
a device used to determine if an object has a charge
Conductor
a material in which charges can move easily
Examples of Conductors
a. Most metals are good conductors
b. Tap water is a conductor, that's why you avoid using electrical devices near water.
Insulator
a material in which charges cannot easily move.
What are 3 ways an object may become charged?
a. Friction
b. Conduction
c. Induction
Examples of Insulators
Plastic, rubber, glass, wood, and air are all insulators
Static Electricity
the buildup of electric charges in an object
Electric Discharge
the loss of static electricity as charges move off an object
Examples of Electric Discharge
a. When you walk on carpet with rubber soled shoes, negative charges build up in your body. WHen you touch a nmetal doorknob, the negative charges in your body move quicklyto the doorknob. Gecause the electric discharge happens quickly, you feel a shock.
b. LIghtning is a dramatic example of electric dischrage