P3 Flashcards

(53 cards)

1
Q

What is electric charge

A

A property of a particle - can be positive or negative

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

What happens when you rub two insulators together

A

Electrons can be transferred
One insulator ends up with more electrons than the other giving it an overall negative charge

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

What is static electricity

A

The charge insulating objects acquire due to the transfer of electrons

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

How do you discharge an object

A

Connect it to something that allows a current to flow (conductor)

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

What are sparks

A

A flow of current and lightning through the airb

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

What is an electric field

A

A field around a charged particle that will attract or repel another charged object even if they are not touching

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

What is current and how do you meausrebit

A

Current is the rate of flow of charged particles

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

How do you make current flow

A

You need a complete circuit containing a cell or battery

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

How does the rope model, model electricity

A

A person pulling the rope is a battery and the movement of the rope is the charge

The person griping the rope represents a circuit component

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

What is conventional current

A

Positive to negative flow of charge

This is opposite to electron flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How do you calculate charge

A

Charge is measured in Coulombs

Charge = current. × time

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

What is potential difference

A

A difference in electrical potential produced by the separation of charge

1v shows 1J of energy transferred per coulomb of charge that is moving through the circuit

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

What happens when you apply p.d to two sides of a wire

A

An electric field is created quickly, so the charged electrons move straight away

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

In a diagram what end of a cell/battery is positive and which is negative

A

Positive - the longer line
Negative - the smaller line

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

How d measure the energy transferred (electrical working) by p.d

A

P.d (volts) × charge

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

What is a series circuit

A

A circuit with one loop
The current is the same throughout all of this loop

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How do you measure amps

A

Using an ammeter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How do you measure volts

A

A voltmeter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What does a voltmeter measure

A

Volts - the rise in potential across a cell or battery / the drop in potential across a component

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How do voltmeters need to be set up in order to show the p.d of a component

A

Connected to both sides of the component

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How do you find the voltage at the cell of a series circuit

A

Add all the voltage (from the components) together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Why is the voltage across a wire zero

A

There is a very little potential difference across wires

23
Q

What is a parallel circuit

A

Having two or more loops

24
Q

What is resistance

A

A measure of how easy it is for current to flow

25
How do you calculate restistance
Using Resistance = p.d ÷ current R= v/I
26
How do you calculate p.d
V = I×R Amps is I
27
Why does the resistance of some components change
Metals are made of positively charged ions in a regular shape These ions are formed when electrons leave the outer shell - and these delocalised electrons move throughout the metals structure Resistance is produced when electrons collide with the ions in a lattice. This is why the resistance of some components change with current (Greater current = faster electrons = more collisions)
28
What is a variable resistor
A resistor that can change the amount of wire or other resisting material - to increase or decrease a circuit resistance
29
Do longer wires have a greater or lower resistance
The longer the wire the greater the resistance
30
What can you use a p.d and current graph to calculate
The resistance
31
What does the graph of a wire or resistor look like
It is a linear graph where the p.d is directionally proportional to the current
32
What is ohms law
The current is directly proportional to the potential difference if the current doesn't change The resistance is constant
33
What does a p.d current graph of a wire look like
Its a non linear graph This is because the wire gets hot, so the resistance is not constant
34
How do filament lamps work
Electrons in a wire collide with ions in a wire. The ions vibrate more as the temperature gets hotter (As the temp increases a glow is produced) As that happens there are more collisions The wire heats up more. The current increases qs p.d increases but at a slower rate
35
What does the current p.d graph of a diode look like
Diodes only work in positive values, so when charge in negative no current is produced When you apply a small amount of positive p.d the current suddenly increases
36
How is an LED connected to a battery
The long leg of an LED is connected to a battery
37
What is a thermistor
A circuit component that has a resistance which depends on temperature Its a semi conductor Resistance decreases when temp increases (Explanation - not needed) Increased temp = increased conduction = increased flow of electrons
38
How does the resistance change with temperature
As the temperature increases the resistance increases
39
How could a thermistor be used in a circuit with a fan
As the outside temperature increases the resistance increases. This means the current must be increasing (to keep p.d the same) This current can then activate the fan (if the fan only turns on above a certain current)
40
What is an LDR
A light dependent resistor Its resistance depends on the light intensity
41
How does the resistance of an LDR change with LI
As light intensity increases, more electrons are released by the semiconductor so resistance decreases (Same for Thermostor)
42
How do you calculate net resistance
It is the total resistance in a circuit Adding components in series increases the net resistance Adding components in parallel decreases the net resistance
43
What are sensing circuits
A circuit which contains a conductor with a resistance that changes with a change to the environment
44
How do you calculate electrical power
Power = p.d × current Power = resistance × current^2
45
How do you calculate energy transferred (using power)
Power × time
46
What happens to current and voltage in series circuits
Current - the current is the same across the whole cell P.d (voltage) - The p.d is split across each component in the circuit. This voltage adds up to the p.d across the battery
47
What is current and p.d like in parallel circuits
Current - The current in each branch (loop) adds up to the current at the battery P.d - the total voltage in each loop is equal to the voltage at the battery
48
What is direct current
Current in a cell moving in one direction
49
What is alternating current
Current in a circuit that is constantly changing at a specific frequency
50
What is the voltage and frequency of alternating current in the uk
Frequency - 50 hertz Voltage - 230v
51
What device is used to view changing p.d
An oscilloscope
52
What is an oscilloscope used for (p3)
It can be used to measure alternating current. It shows a graph of p.d against time, where the p.d is constantly changing between positive and negative values
53
How do you calculate resistance in parallel
Total resistance = 1/r1 + 1/r2 ....