unit 1.5 - electric circuits REMASTERED

Question 1

describe current

Answer 1

flow of electrons around a circuit

Question 2

describe voltage

Answer 2

the ‘driving force’ that pushes the current around the circuit

Question 3

describe resistance

Answer 3

anything in the circuit that opposes/ slows down the flow of current

Question 4

increasing the voltage will _____ the current flow

Answer 4

increase

Question 5

increasing the resistance will _____ the current flow

Answer 5

decrease

Question 6

the ammeter measures current ________ a component and must be placed in ______ with the component

Answer 6

through

series

Question 7

the voltmeter measures voltage ________ a component and must be placed in ______ with the component

Answer 7

across

parallel

Question 8

another word for voltage is

Answer 8

potential difference (pd)

Question 9

in a series circuit
the total resistance is equal to…

Answer 9

…the sum of all resistances

Question 10

in a series circuit
the same _____ flows through all parts of the circuit

Answer 10

current

Question 11

in a series circuit
the supplied voltage is equal to…

Answer 11

…the total voltage across all components

Question 12

in a series circuit
the bigger the resistance of a component…

Answer 12

…the bigger its share of the supply voltage

Question 13

in a parallel circuit
the _______ is the same across all components

Answer 13

voltage

Question 14

in a parallel circuit
the total current around the circuit is equal to…

Answer 14

…the sum of all currents flowing through the branches

Question 15

in a parallel circuit
the lower the resistance of a component…

Answer 15

…the higher the current through it

Question 16

in a parallel circuit
the current either ___ or _____ where branches meet. The total current going in to a junction must equal…

Answer 16

splits , rejoins
…the total current leaving it

Question 17

in a parallel circuit
the total resistance of the circuit is always less than…

Answer 17

…the lowest branch resistance

Question 18

The [longer/shorter] the wire, the greater the resistance

Answer 18

longer, more atoms for electrons to collide with, slowing down current

Question 19

the [thicker/thinner] the wire, the smaller the resistance (width)

Answer 19

thicker, more paths for electrons between atoms, increasing current

Question 20

the [hotter/colder] the wire, the greater the resistance (temperature)

Answer 20

hotter, hotter atoms vibrate more causing more collisions with electrons

Question 21

How to calculate total resistance in series

Answer 21

R = R1 +R2 + R3 + …

Question 22

How to calculate total resistance in parallel

Answer 22

R = 1/R1 + 1/R2 + 1/R3 + …

Question 23

What is Ohm’s law

Answer 23

‘The voltage across a metal conductor is proportional to the current through it, provided the temperature stays constant’

Question 24

how are V, I and R related? (not equation)

Answer 24

The large the resistance, the greater the voltage needed to push current through

Question 25

Voltage equation

Answer 25

V = I x R

Question 26

show an example of a standard test circuit

Answer 26

-----------|l--------------- l l l [/] l l -----x------------A--------- l--V--l x - component A - Ammeter [/] - variable resistor |l - battery V - voltmeter

Question 27

VI graph about resistor shows? Does it obey Ohm's law?

Answer 27

a) The current through a resistor is proportional to voltage (temps constant) / Ohms law b) Yes

Question 28

VI Graph for resistor how does current vary as voltage increases?

Answer 28

current is proportional to voltage (if temp is constant)

Question 29

VI Graph for wire how does current vary as voltage increases?

Answer 29

Different graph gradients, but all obey ohm's law (if temp is constant)

Question 30

VI Graph for filament lamp how does current vary as voltage increases?

Answer 30

as more current flows in the lamp, the filament gets hotter, causing the resistance to increase. Doesnt obey ohm's law

Question 31

VI Graph for diode how does current vary as voltage increases?

Answer 31

When connected in forward direction, diode has low resistance, allowing current to flow. When reversed, it has a high resistance and stops current flowing. Doesn't obey ohm's law

Question 32

VI Graph for thermistor how does current vary as voltage increases?

Answer 32

Thermistor is a semiconductor, conducting electricity when heated as more electrons are made available to carry current, decreasing the resistance. Doesn't obey ohm's law

Question 33

VI Graph for LDR how does current vary as voltage increases?

Answer 33

LDR is a semiconductor, conducting electricity when light shines on it, as more electrons are made available to carry current, decreasing the resistance. Doesn't obey ohm's law

Question 34

which way does the current flow if battery is like this ----------|l---------

Answer 34

<---

Question 35

the steeper a VI graph, the _____ the resistance

Answer 35

lower

Question 36

What is power

Answer 36

amount of energy transferred each second

Question 37

energy (kWh) equation

Answer 37

E = P x t

Question 38

power equation

Answer 38

P = V x I

Question 39

cost of electricity equation

Answer 39

cost of electricity = kWh x cost per unit