Energy, Power and Resistance Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

How are Kirchoff’s laws applied to series circuits?

A
  • current same everywhere

- EMF shared across components

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How are Kirchoff’s laws applied to parallel circuits?

A
  • current splits across branches

- voltage same everywhere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How is resistance calculated in series circuits?

A

resistance of resistors added up

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How is resistance calculated in parallel circuits?

A

Rt = (1/r1) + (1/r2) etc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How does resistance restrict the flow of charge?

A

repeated collisions between charge carriers and other materials

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is ohms law?

A

potential difference is directly proportional to current as long as temperature is constant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Define resistance:

A

the potential difference needed to make 1 ampere of current flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the IV characteristics of a fixed resistor?

A
  • directly proportional

- steeper gradient = less resistance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the IV characteristics of a filament lamp?

A
  • non ohmic

- as current increases heating effect on metal ions causes resistance to increase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the IV characteristics of diodes?

A
  • resistance rapidly decreases as potential difference is above threshold value as number density of charge carriers increases
  • anything other than positive I or V the resistance is too high therefore no current flows
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the IV characteristics of thermistors?

A

resistance decreases as temperature increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the IV characteristics of LDRs?

A

resistance decreases as light intensity increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are sensors?

A

component that allows a physical quantity to change its resistance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What can change depending on an LEDs colour?

A

threshold PD

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Define resistivity:

A

materials opposition to the flow of charge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the relationship between resistance and resistivity?

A

directly proportional

17
Q

What is the relationship between resistance and length of wires?

A

directly proportional

18
Q

What is the relationship between resistance and cross sectional area of a wire?

A

inversely proportional

19
Q

What is transferred when there is current in a component?

A

energy

20
Q

What is an electricity meter?

A

records transfer of energy from national grid to house

21
Q

What does the cost of electricity depend on?

A

power and duration of device used

22
Q

Define kilowatt hour:

A

energy transferred by a device of power 1kW operating for a time of 1 hour

23
Q

What does 1kWh equal?

A

3.6MJ

24
Q

What is the average cost per kWh?

A

6-15p