CHAPTER 9

Question 1

CAPACITOR

Answer 1

a component that stores charge, consists of two plates separated by an insulator

Question 2

CELL

Answer 2

a device that transfers chemical energy into electrical energy

Question 3

BATTERY

Answer 3

a collection of cells that transfers chemical energy into electrical energy

Question 4

SERIES

Answer 4

an arrangement of electrical components connected end-to-end, meaning the current is the same in each component

Question 5

POLARITY

Answer 5

the type of charge (positive or negative) or the orientation of a cell relative to a component

Question 6

POTENTIAL DIFFERENCE

Answer 6

defined as the energy transferred from electrical energy to other forms (heat, light, etc.) per unit charge

Question 7

VOLT

Answer 7

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

Question 8

VOLTMETER

Answer 8

a device used to measure potential difference- it must be placed in parallel across the components and ideally have an infinite resistance

Question 9

ELECTROMOTIVE FORCE

Answer 9

the work done on the charge carriers per unit charge, measured across a cell, battery or power supply

Question 10

ELECTRON GUN

Answer 10

a device that uses a large accelerating potential difference to produce a narrow beam of electrons

Question 11

THERMIONIC EMISSION

Answer 11

the emission of electrons from the surface of a hot metal wire

Question 12

RESISTOR

Answer 12

an electrical component that obeys Ohm’s law, transferring electrical energy to thermal energy

Question 13

OHM

Answer 13

the derived SI unit of resistance, defined as the resistance of a component that has a potential difference of 1 V per ampere

Question 14

OHM’S LAW

Answer 14

the potential difference across a conductor is directly proportional to the current in the component as long as its temperature remains constant

Question 15

FILAMENT LAMP

Answer 15

an electrical component containing a narrow filament of wire that transfers electrical energy into heat and light

Question 16

I-V CHARCATERISTIC

Answer 16

a description of the relationship between the electric current in a component and the potential difference across it

Question 17

OHMIC CONDUCTOR

Answer 17

a conductor that obeys ohms law

Question 18

NON- OHMIC COMPONENT

Answer 18

a component that does not obey ohms law, e.g. a filament lamp and a diode

Question 19

LIGHT- EMITTING DIODE

Answer 19

a type of diode that emits light when it conducts electricity

Question 20

DIODE

Answer 20

a semiconductor component that allows current only in one particular direction

Question 21

THRESHOLD VOLTAGE

Answer 21

the minimum potential difference which a diode begins to conduct

Question 22

RESISTIVITY

Answer 22

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

Question 23

THERMISTOR

Answer 23

an electrical component that has a resistance that decreases as the temperature increases (a negative temperature coefficient)

Question 24

NEGATIVE TEMPERATURE COEFFICIENT

Answer 24

a relationship in which a variable decreases as the temperature increases

Question 25

LIGHT- DEPENDANT RESISTOR

Answer 25

an electrical component with a resistance that decreases as the light intensity incident on it increases

Question 26

ELECTRICITY METER

Answer 26

a device that measures the electrical energy supplied in kWh to a house from the grid

Question 27

KILOWATT- HOUR

Answer 27

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