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Science > Wh Y9 HT 1 > Flashcards

Wh Y9 HT 1 Flashcards

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1
Q

Magnetic field

A

A region magnetic objects have around them where the magnetic force can be felt.

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2
Q

The 3 magnetic elements at room temperature:

A

Iron(Fe)
Nickel(Ni)
Cobalt(Co)

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3
Q

Steel is made of what

A

C + Fe

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4
Q

What does sulphur do when bound with iron

A

Removes its magnetism as it becomes iron sulphide

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5
Q

North Pole on a magnet:

A

North seeking

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6
Q

South Pole on a magnet:

A

South seeking

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7
Q

North and south poles can __________…

A

Interact with eachother or put force on eachother

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8
Q

Like poles

A

Repel

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9
Q

Unlike poles

A

Attract

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10
Q

The arrows on a magnetic field bar magnet diagram show what

A

The force feels if another North Pole was there

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11
Q

When two north poles are next to eachother in the centre is

A

A neutral point of no magnetic force due to the fields cancelling eachother out (destructive interference)

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12
Q

When a north and a South Pole are next to eachother

A

Lots of parallel lines of flux so high flux density so the field strength is strong. It is also constant

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13
Q

Why does the earth have its own magnetic field?

A

Because the core is made of iron

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14
Q

Where is the earths magnetic field weakest

A

Along the equator

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15
Q

The earths magnetic field does what to protect us from the sun

A

It deflects the suns’ rays

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16
Q

What can an EM do that a normal magnet can’t?

A

Have its magnetism switched on or off

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17
Q

How to make an EM

A

Soft magnetic core (soft iron/pure iron)

Wrapped in current carrying wire to create and EM

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18
Q

Another name for an EM

A

A solenoid

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19
Q

How to turn an EM on

A

Apply DC current through the coil. This aligns the domains

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20
Q

How to turn an EM off

A

You can’t just turn off the DC current as there will still be residual magnetism so we apply AC current to unaligned the domains and demagnetise it

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21
Q

How to increase an EM’s strength

A

More coils per unit length
Increase current input
Choose a core with a higher permeance

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22
Q

Permeance

A

The ability of an object to accept or amplify a magnetic field

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23
Q

How many times does AC current change direction from the plugs?

A

About 50 times per second, 50Hz

24
Q

Uses of an EM

A 
Electric doors
Fire bells
Train joins
Hover boards
MRI scans
DC motors
Generators
Speakers
Doorbells
25
Q

Motors’ energy transfer:

A

El to ke

26
Q

How does a DC motor work

A

See book for diagram etc.

27
Q

How to reverse the spin of a DC motor

A

Make the current flow in the opposite direction round the circuit
Or reverse the permanent magnet

28
Q

Graph- physics

A

Title- A graph showing the …
X axis- independent
Y axis- dependant

29
Q

Increase the rate of spin for a DC motor

A

Increase the voltage which increases the current which increases the magnetic field which increases the forces and therefore makes it spin faster

30
Q

Another name for a generator

A

A dynamo

31
Q

Generator energy transfer

A

Ke to EL

32
Q

Generator can be described as what

A

A motor in reverse

33
Q

Electromagnetic induction

A

process of moving a magnet into a coil of wire to produce a volatage

34
Q

Faraday’s law

A

States that potential difference is induced across a wire producing electric current when a coil of current carryon wire cuts through a magnetic field or a magnetic field is cut through a coil of wire

35
Q

To increase induced voltage

A

Increase spin speed

Increase coils per unit length

36
Q

Hydro

A

Situated in rivers. Water flows downstream pushed through the dam and spins turbines
maximises on GPE
GPE ke el

37
Q

Tidal

A

Tidal barrage- Dam structure created sea tide passes under it and sound turbines
Gpe ke el

38
Q

Wind

A

Onshore and offshore
Wind turns big turbine
Ke el

39
Q

Nuclear

A

235 uranium or 239 plutonium nuclei absorb a neutron setting off a chain reaction of the nuclei splitting 3 neutrons being released and energy being released. The thermal energy heats up water and turns to gas which spins a turbine
Nu th ke el

40
Q

Geo thermal

A

In volcanic active areas hot rocks under the crust. When they decay steam rises and spins turbines else water poured down and is heated and turned into steam
Th ke el

41
Q

Wave

A

The movement of seawater in and out of a cavity on the shore compresses trapped air, driving a turbine.
Ke el

42
Q

Biomass

A

Burning dead organic matter (wood, ethanol, plants etc.)

Th el

43
Q

Solar

A

Photovoltaic cells light energy is absorbed by the pc cells. Uses difference in conductivity between the silicon in it to generate a voltage
Solar power tower- light and heat from the sun is reflected from the mirrors up to a solar collector. Heat boils water etc. Nuc th ke el

44
Q

Sankey diagrams show what

A

Energy transfers useful and wasted energy

45
Q

Sankey diagrams’ thickness shows

A

The amount of energy

46
Q

Kettles waste little amounts of energy because

A

Insulated

Anchored base to stop movement

47
Q

Energy =

kWh

A

Power x time

kW. Hrs

48
Q

Cost of energy =

p

A

Energy used x cost per kWh

kWh. P/kWh

49
Q

Filament lamp-

A

Creates light by pushing current through a wire which gets hot and glows releasing light

50
Q

Filament

A

Wire of tungsten

51
Q

Lamp in circuit

A

X in a circle

52
Q

Variable supply (power)

A

Circle then arrow pointing diagonally up right then circle

53
Q

Ammeter symbol

A

A in a circle

54
Q

Voltmeter symbol

A

V in a circle

55
Q

Ohms law

A

Resistance

Ohms

Science (2 decks)

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