Unit 1.5 - Electric Circuits

Question 1

When more bulbs are added to series circuit, the current…

Answer 1

…decreases

Question 2

When more batteries are added to series circuit, the current…

Answer 2

…increased

Question 3

When the current increases, the lamps got…

Answer 3

…brighter

Question 4

When the current decreased, the lamps got…

Answer 4

…dimmer

Question 5

This is a battery, which way does the current flow:
——|l——

Answer 5

<—-

Question 6

This is a battery, where does the current flow:
——-l|———-

Answer 6

—>

Question 7

In a series circuit, current

Answer 7

Is the always the same

Question 8

In a series circuit, voltage

Answer 8

Is different across each component. It adds up to the total voltage supplied

Question 9

In a parallel circuit, current

Answer 9

Splits in half at each junction then combine at the end

Question 10

In a parallel circuit, voltage

Answer 10

Always Stays the same

Question 11

What creates resistance

Answer 11

When electrons can’t pass through the gaps between wire particles

Question 12

As you increase resistance, current

Answer 12

Decreases

Question 13

If resistance is doubled, current

Answer 13

Divides in half

Question 14

Which two things is current proportional to

Answer 14

Voltage - directly

Resistance - inversely

Question 15

Resistance higher in short or long wire?

Answer 15

Long - more particles, more frequent collisions, less electrons passing, less current, more resistance

Question 16

Resistance higher in thick or thin wire?

Answer 16

Thin -less paths between particles, less electrons likely to pass, current decreases, resistance increases

Question 17

Resistance higher in wire with a few electrons or lots of electrons?

Answer 17

Few electrons-less current flows with electrons, resistance is high

Question 18

What are materials with no electrons called

Answer 18

Insulators

Question 19

Resistance higher at low or high temp

Answer 19

High temp - particles have more energy, vibrate more, don’t get bigger, take up more room, less space for electrons to pass, less current, resistance higher

Question 20

How to add up resistance in series circuit

Answer 20

R = R1 + R2 + R3 …

Question 21

How to add up resistance in parallel circuit

Answer 21

1/R = 1/R1 + 1/R2

R = R3 + R4 + (1/R1 + 1/R2)

Question 22

Equation connecting R, I, V

Answer 22

R = V/I

Question 23

Example of Standard test circuit

Answer 23

———- |l —————
l. l
l. l
/. [\]
l. l
l———A——-X——-l
l—-V—-l

Question 24

What does each of the components do in a standard test circuit

Answer 24

Ammeter-measures current through the component
Volt meter-measures voltage across component
Variable resistor-used to change current flowing in circuit
Component- what is tested

Question 25

On a VI graph, which line has a lower resistance, steeper or not

Answer 25

Steeper

Question 26

VI graph for filament lamp - what happens as voltage increases

Answer 26

More current flows in lamp causing thin wire filament to increase in temp, increasing resistance-shown by decrease in gradient on VI graph

Question 27

VI graph for diode - What happens as voltage increases

Answer 27

A diode only allows current to flow in One Direction, Because of this current will only flow if the threshold voltage is reached, meaning V a graph will be constant at first then become steeper shortly after.

Question 28

How does a diode work?

Answer 28

When connected forward, it has low resistance (no current). When reversed it has high resistance (current flows)

Question 29

VI graph for LDR-what happens when voltage across LDR decreases

Answer 29

LDR is a semiconductor. Under bright light more electrons are free to carry charge, resistance is low.(steep graph) Under dark conditions, resistance is high (less steep graph)

Question 30

V I graph for thermistor-what happens as temperature increases

Answer 30

Resistance decreases as thermistor is a semiconductor. As the temperature increases more electrons are free to carry charge therefore decreasing resistance

Question 31

Equation connecting power, energy transfer, time

Answer 31

P = E/t

Question 32

One watt is worth

Answer 32

1 J/s

Question 33

Equation connecting power voltage and current

Answer 33

P = V x I

Question 34

Equation Used to calculate kWh 

Answer 34

kWh = P x t

Question 35

Cost of electricity equation

Answer 35

Cost = kWh x cost per unit