Electrical circuits

Question 1

alternating current

Answer 1

a current that continually changes direction (powered by generators)

Question 2

ammeter

Answer 2

connected in a series cicruit and is used to measure amps

Question 3

ampere

Answer 3

the unit of current

Question 4

conductor

Answer 4

a material that allows electrical charge to flow easily

Question 5

coulomb

Answer 5

the unit of charge

Question 6

currents at a junction

Answer 6

the sum of the currents entering a junction must always equal the sum of the currents leaving it

Question 7

diode

Answer 7

a component that only allows current to flow through in the forward direction. they have a very large resistance in the reverse direction

Question 8

direct current

Answer 8

current flows in one direction only (powered by batteries and cells)

Question 9

earthing

Answer 9

the removal of excess charge by providing a low resistance path for electrons to flow through

Question 10

electric current

Answer 10

the rate of flow of electrical charge. I = Q/t

Question 11

filament lamp

Answer 11

a light emitting component consisting of an enclosed metal filament. its resistance increases as the filaments temperature increases

Question 12

fuse

Answer 12

a safety device consisting of a thin metal filament that melts and cuts off the power supply if there is a surge in current. They are connected to the live wire

Question 13

insulator

Answer 13

a material that doesnt allow electrical charge to flow

Question 14

light dependent resistor (LDR)

Answer 14

a light sensitive component whose resistance decreases as the light intensity increases

Question 15

light emitting diode

Answer 15

a device that gives out light when a current flows through it. current can only flow through it in one direction, a a minimum voltage must be applied across it before it illuminates

Question 16

live wire

Answer 16

the brown coloured wire that carries the alternating current from the supply in a mains power supply

Question 17

ohm

Answer 17

a unit of resistance

Question 18

ohms law

Answer 18

the current flowing through an ohmic conductor at constant temperature is directly proportional to the potiential difference across it (basically, current is directly proportional potential difference)

Question 19

potential difference

Answer 19

the work done by a unit charge passing through a component in a circuit. V = IR

Question 20

power

Answer 20

the rate at which an appliance transfers energy. P = IV or P = J/t

Question 21

resistance

Answer 21

how difficult it for a charge to flow. R = V/I

Question 22

resistors in parallel

Answer 22

the total resistance is less than the lowest individual resistance. Rt = (1/R1 + 1/R2)^-1

Question 23

resistors in series

Answer 23

the total resistance is equal to the sum of the resistances of the individual resistors. Rt = R1 + R2

Question 24

series

Answer 24

components connected in series have the same current passing through each component by share the total potential difference of the power supply

Question 25

thermistor

Answer 25

a temperature dependent component, whose resistance increases as its temperature decreases

Question 26

volt

Answer 26

the unit of potential difference. 1V = 1J/1C

Question 27

Voltmeter

Answer 27

a device connected in parallel with a component to measure the potential difference across it

Question 28

watt

Answer 28

the unit of power

Question 29

EMF

Answer 29

electrical work done by a source in moving a unit charge around a complete circuit

Question 30

Energy

Answer 30

the capacity of something to do work. J = Wt

Question 31

joule

Answer 31

the unit of energy

Question 32

Charge

Answer 32

a property of a body which experiences the electrostatic field force. Q = It

Question 33

electrical work done formula

Answer 33

W = QV, work done = charge x potential difference