Chapter 7: Electricity and Magnetism Flashcards
1
Q
What is energy?
A
The ability to do work
2
Q
State the forms of energy. (9)
A
- Nuclear
- Heat
- Light
- Kinetic
- Chemical
- Electrical
- Sound
- Chemical
- Gravatational potential
- Elastic potential
3
Q
State the sources of energy.
A
- Sun
- Geothermal
- Water
- Biomass
- Radioactive substance
- wave
- wind
- fossil fuel
4
Q
What is geothermal?
A
heat from inside the earth
5
Q
How is biomass obtained?
A
remains of animals and plants
6
Q
How is fossil fuels obtained?
A
-remains of the dead plants and animals
7
Q
What are the 3 charges of electricity?
A
electron, proton and neutron
8
Q
Does electron move?
A
yes
9
Q
Does proton moves?
A
no
10
Q
What will happen if the objects rubs the other?
A
Being rubbed- gain electron
Rubbing- loses electron
11
Q
Like charges attract or repel?
A
repel
12
Q
What is the function of an electroscope?
A
to detect the existence of electric charges on an object.
13
Q
What will happen if a neutral strip is on the copper plate?
A
Gold leaf will not diverge, bc positive and negative are attracted
14
Q
What will happen if a positively charged strip is on the copper plate?
A
it’ll diverge as same charges repel.
15
Q
What will happen if a negatively charged strip is on the copper plate?
A
it’ll diverge as same charges repel.
16
Q
How does lightning conductors work?
A
- negative charges travels down to the earth
- lightning conductors contain positive charges
17
Q
Why should we avoid wearing wool, polyester and nilon?
A
they are good at generating and holding electrostatic charge.
18
Q
Why should we touch the metal part of the vehicles before pumping oil.
A
-to drain charges from the body to the ground
19
Q
What is a Faraday cage?
A
earthed metal screen to remove electrostatic charges
20
Q
What is the solution to the friction between the tank and the air?
A
metal chains are fixed to the back of the petrol tanker
→ enable charges to flow to Earth
21
Q
What is an electric current?
A
the rate of flow of electric charges through conductor
22
Q
What produced electric current?
A
charges flow in an electrical conductor
23
Q
From where to where electrons flow?
A
from negative terminal to positive terminal.
24
Q
From where to where electric current flow?
A
from positive terminal to negative terminal.
25
what is formed on the dome on the Van de Graff generator?
positive charges
26
What produces an electric current through galvanometer in Van de Graff generator?
the flowing of electrons
27
What is the use of ammeter?
measure electric current
28
Is there a suggestion that ammeter needs to connect to a specific circuit?
yes, series circuit
29
What is the use of voltmeter?
measure voltage
30
Is there a suggestion that voltmeter needs to connect to a specific cicuit?
yes, parallel circuit
31
What is voltage?
the force that moves charges from one point to another
32
What is the relationship between voltage and current?
the higher the voltage, the higher the current.
33
What are a group of dry cells?
battery
34
What is the relationship between volt and brightness?
the higher the volt, the brighter it is
35
What is the relationship between amphere and brightness?
the higher the amphere, the brighter it is
36
What is the relationship between resistance and current?
The larger the resistance, the smaller the current flow
37
What is resistance?
the ability of a conductor to limit or resist the flow of electric current
38
What does the resistance of conductor depends on?
```
MLDT
Material
Length
Diameter
Temperature
```
39
What is a resistor?
An electrical component that resists the flow of current in the circuit
40
What is the Ohm's Law?
V=I x R
41
What is voltage, current and resistance's symbol?
```
Voltage = V
Current = A
Resistance = Ω
```
42
What is an electric circuit?
A complete path which enables electric current to flow
43
State the symbols of a cell, battery, switch, bulb, buzzer, ammeter, voltmeter, motor, resistor and variable resistor
https://drive.google.com/file/d/1ZaLWDLzfHI9fnJoq00cwVTyG49gfX1-p/view?usp=sharing
44
What is series circuit in chinese?
串联
45
What is parallel circuit in chinese?
并联
46
Are all the current same in series circuit?
Yes
47
Are all the voltage same in series circuit?
No, the sum is the total voltage
48
Are all resistance same in series cicuit?
No, the sum is the total resistance
49
Why are all the current same in parallel circuit?
Bc all lamps are equal in brightness
50
What is the benefit of using series circuit?
- save wires
- controlled using only one switch
- Equal brightness
51
What would happen if more dry cells are connected in series?
The voltage across each electrical component increase, the brightness of the bulbs increases
52
What are the disadvantages of series circuit?
- if one bulb spoils, all others will not function
- Each electrical component cannot be controlled individually
- when there is more electrical component, the resistance increases while the current decreases
53
Are all the current same in parallel circuit?
No, the total is the sum of all currents
54
Are all the voltage same in parallel circuit?
Yes
55
Are all the resistance same in parallel circuit?
No, 1/R= 1/R1 + 1/R2 +1/R3
56
What are the advantages of a parallel circuit?
- If one spoils, others can still light up
- Each electrical component can be controlled indicidually
- If the electrical components increase, the function of other components are not affected
57
What are the disadvantages of parallel circuit?
- too many wires
| - more bulbs, dry cells become weak and decreases faster
58
What would happen if more electrical components are connected in parallel circuit?
- voltage remains
- brightness same
- battery dries out quicker
59
What is a magnet?
A substance that can produce a magnetic field and attract materials with magnetic properties.
60
State some material with magnetic properties.
- nickel
- iron
- cobalt
61
State the properties of magnet (4)
- attracts magnetic objects
- has north and south poles
- freely suspended magnet shows north-south direction
- same poles repel, opposite poles attract each other.
62
Can gold, silver and copper be attracted by magnet?
No
63
Does magnetic poles come individually or in pairs?
ALWAYS in apirs
64
Where will the south pole of magnet point to when hung freely?
Geografically north of Earth
65
Where will the south pole of magnet point to when hung freely?
Geografically south of Earth
66
What is a magnetic field?
The area where the force of magnetism acts on another magnet or magnetic object
67
State the 3 characteristics of magnetic field lines
- does not cross one another
- begins at north pole, ends at south pole
- lines are closer at the poles of magnet.
68
State the relationship between the magnetic field lines and the magnetic field.
The closer the lines, the sronger the magnetic field
69
What is a magnadur magnet?
ceramic magnets with their poles on their flat faces. (Example: fridge magnets)
70
What does the direction of the compass needle shows?
the direction of magnetic field
71
What is the point that doesn't have any magnetic field called?
neutral point
72
What is an electromagnet?
A material that has temporary magnetic effect when the electric current flows through the conductor.
73
What is the relationship between the coverage of copper and the magnetic effect?
The more the copper wire covers, the stronger the magnetic effect.
74
What is the relationship between current flow and magnetic effect?
When the current flows, magnetic effect is shown, if not, it'll dissappear.
75
What does the pattern and direction of magnetic field depends on?
-shape of conductor
76
For straight wire, state the relationship between magnectic field and the current.
The magnetic is the strongest when close to the current and weaker when it furthur away
77
State the pattern of magnetic field for straight wire.
circular magnetic field pattern
78
What is the right hand grip rule?
method used to determine the direction of magnetic field by the direction of electric current.
79
State the direction of magnetic field for straight wire if the current goes up.
anti-clockwise
80
State the relationship between the magnetic field lines and magnetic field of coiled wire
Magnetic field is the strongest at the centre of the coil as magnetic field lines are closer
81
State the pattern of magnetic field lines in the middle of coiled wire
straight
82
Where is the magnetic field strongest in solenoid?
inside of the solenoid/ centre
83
How to determine the direction of magnetic field in solenoid?
-Right-hand grip rule
→thumb points to north pole
→rest of fingers indicate the direction of current
-Looking at the current
→if current flows in clockwise, it's south pole
→If current flows in anti-clockwise, it's north pole
84
What are the factors that influence the strength of electromagnet?
- Magnitude of current
| - Number of coils
85
State the relationship between the current and the electromagnet.
The larger the amount of current, the stronger the electromagnet
86
State the relationship of number of coils and the electromagnet.
The more the number of coils, the stronger the electromagnet.
87
State 2 of the uses of magnet in everyday life.
- Compass
| - Maglev train
88
What is the use of compass?
to determine direction of north,east,south,west using the magnet
89
What is the benefit of using maglev tran?
- minimal resistance
| - high speed
90
How does maglev train move?
- one set of magnet repels and push the train up, off track
| - another set to move by changing it's pole.
