CHAPTER 9 Flashcards
CAPACITOR
a component that stores charge, consists of two plates separated by an insulator
CELL
a device that transfers chemical energy into electrical energy
BATTERY
a collection of cells that transfers chemical energy into electrical energy
SERIES
an arrangement of electrical components connected end-to-end, meaning the current is the same in each component
POLARITY
the type of charge (positive or negative) or the orientation of a cell relative to a component
POTENTIAL DIFFERENCE
defined as the energy transferred from electrical energy to other forms (heat, light, etc.) per unit charge
VOLT
the derived SI unit of potential difference and electromotive force, defend as the energy transferred per unit charge- 1 V is the p.d. across a component when 1 J of energy is transferred per 1 C passing through the component
VOLTMETER
a device used to measure potential difference- it must be placed in parallel across the components and ideally have an infinite resistance
ELECTROMOTIVE FORCE
the work done on the charge carriers per unit charge, measured across a cell, battery or power supply
ELECTRON GUN
a device that uses a large accelerating potential difference to produce a narrow beam of electrons
THERMIONIC EMISSION
the emission of electrons from the surface of a hot metal wire
RESISTOR
an electrical component that obeys Ohm’s law, transferring electrical energy to thermal energy
OHM
the derived SI unit of resistance, defined as the resistance of a component that has a potential difference of 1 V per ampere
OHM’S LAW
the potential difference across a conductor is directly proportional to the current in the component as long as its temperature remains constant
FILAMENT LAMP
an electrical component containing a narrow filament of wire that transfers electrical energy into heat and light
I-V CHARCATERISTIC
a description of the relationship between the electric current in a component and the potential difference across it
OHMIC CONDUCTOR
a conductor that obeys ohms law
NON- OHMIC COMPONENT
a component that does not obey ohms law, e.g. a filament lamp and a diode
LIGHT- EMITTING DIODE
a type of diode that emits light when it conducts electricity
DIODE
a semiconductor component that allows current only in one particular direction
THRESHOLD VOLTAGE
the minimum potential difference which a diode begins to conduct
RESISTIVITY
a property of a material, defined as the product of the resistance of a component made of the material and its cross- sectional area divided by its length
THERMISTOR
an electrical component that has a resistance that decreases as the temperature increases (a negative temperature coefficient)
NEGATIVE TEMPERATURE COEFFICIENT
a relationship in which a variable decreases as the temperature increases
LIGHT- DEPENDANT RESISTOR
an electrical component with a resistance that decreases as the light intensity incident on it increases
ELECTRICITY METER
a device that measures the electrical energy supplied in kWh to a house from the grid
KILOWATT- HOUR
a derived unit of energy, most often associated with paying for electrical energy. 1 kWh = 3600 J, energy can be calculated by multiplying the power in kW by the time in hours
