Extras Flashcards

1
Q

What do simple levers make it easier to do

A

Easier to do work by moving the distance the force is applied further from the pivot

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2
Q

Where are pendulums used

A

Clocks, playground swings, fairground rides

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3
Q

What is cross section area in a hydraulic measured in

A

M^2

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4
Q

What is velocity

A

Both the speed and direction of an object

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5
Q

Example of a centripetal force using friction

A

A car going round a bend.

Friction between the cars tyres and the road

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6
Q

What can magnetic fields be represented by

A

Field diagrams - the arrows on them always pint from North Pole to the South Pole

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7
Q

What is a magnetic field made up of

A

Concentrated circles with the wire in the centre

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8
Q

How to work out which way the magnetic field is going around a wire

A

The right hand thumb rule where you curl your hand and your thumb points the way of the current and the direction your fingers are curled shows the direction of the field

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9
Q

How can you increase the strength of the magnetic field around a coil of wire (a solenoid)

A

Adding a magnetically soft iron core through the middle of the coil (an electromagnet is formed)

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10
Q

What are electromagnets used in

A

Electric bells, car ignition circuits and some security doors

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11
Q

What way does current flow usually

A

From +ve to -ve

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12
Q

What does electric motors use the motor effect for

A

To get them and keep them moving

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13
Q

How do electric motors help make CD players, food mixers, fan heaters, fans, printers, drills, hair dryers, cement mixers work

A

Link the coil to an axle and the axle spins round.
This can be attached to a fan, a blade or whisk, the bit you sit the cd on.
Fan heaters and hair dryers have an electric heater as well as a fan.

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14
Q

Why will a freely suspended object swing until it’s centre of mass is vertically below the point of suspension

A

Objects weight acts at a distance from the pivot which creates a moment around the pivot so it swings.
Until centre of mass is at its lowest then it rests in this position because there’s no moment.
The pivot is in line with the line of action of the force.

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15
Q

What is the wiring to a three pun plug

A
  • the right coloured wire is connected to each pin and firmly screwed
  • no bare wires in the plug
  • cable grip tightly fastened over the cable outer layer
  • depending on the appliance have the right cable size because thicker cables have less resistance so they carry more current
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16
Q

Why are parts of the plug made of metal like copper and brass

A

Because they are good conductors

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17
Q

What are two important effects of gravity

A

Gives everything a weight

Makes everything accelerate towards the ground

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18
Q

What is weight measured using

A

A sprint balance or Newton metre as its in newtons

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19
Q

What is mass measured using

A

A mass balance as its in Kg

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20
Q

What is the gravity on the moon

A

1.6 N/kg

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21
Q

What is an example of a circuit breaker

A

Residual current circuit breaker

RCCB

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22
Q

How do RCCBs operate

A

Detecting a different in he current between the live and neutral wire

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23
Q

If an appliance is double insulated what does this mean

A

It has no earth wire connection - only metal cased ones do

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24
Q

What is extension of a spring measured by

A

Metres

25
Q

What is the limit of proportionality

A

The maximum force an elastic object can take and still extend proportionately

26
Q

What is momentum

A

The property of moving objects

27
Q

What is a closed system

A

No external forces are acting on it

28
Q

What is the conservation of momentum

A

The total momentum before is the total momentum after

29
Q

How do u find velocity in the momentum

A

Chose which direction is positive
Find total momentum before collision - the one who is going in the negative way will have a minus force
And then if the tmb = tma you can work out the velocity

30
Q

What does aerodynamic mean

A

They are shaped in such a way that air flows very easily and smoothly past them

31
Q

If the resistance in a component increases what happens to the current

A

The smaller the current that flows

32
Q

By varying the variable resistor what happens

A

It alters the current letting you take several pairs of readings from the A and V

33
Q

What is a diode made of and what is it used for

A

Semiconductor material such as silicon and to regulate the potential difference. Useful in electronic circuits

34
Q

Why are led used a lot

A

They use a smaller current than other forms of lighting

35
Q

Where are thermistors used

A

Car engine temperature sensors, electronic thermostats

36
Q

How to work out current in a series circuit

A

Total voltage divided by resistance

37
Q

What is electric current

A

The movement of charge carriers

38
Q

What does the gain dial control

A

How many volts each centimetre division represents on the vertical axis

39
Q

What does the time base dial control

A

How many milliseconds each division represents on the horizontal axis

40
Q

When do cuss ratings needed for cables increase

A

With cable thickness

41
Q

What are cables known as that only carry the live and neutral wire

A

Two core cables

42
Q

How do filament bulbs work

A

Passing a current through a very thin wire heating it up so it glows

43
Q

How to work out power rating of appliances

A

Energy transferred divided by time

44
Q

What experiment did Rutherford and marsden do

A

They beamed alpha particles at a thin sheet of gold foil expecting them to be slightly deflected but most went straight back through and a few shot completely back. Realised most of mass in nucleus and atom was empty space.

45
Q

What is half life

A

The average time it takes for half the number bed of nuclei in a radioactive isotope sample to halve

46
Q

What is radiotherapy

A

Treatment of cancer using gamma rays

47
Q

How can X-ray images be formed electronically

A

Using charged coupled devices (CCDs)

48
Q

How do CCDs work

A

They are silicon chips the size of a postage stamp. They detect X-rays and produce electronic signals which are used for high resolution images like in s camera

49
Q

When working out the power of the two lenses which was is negative and which is positive

A

Negative is diverging

Positive is converging

50
Q

What are lasers used to treat besides eyes and cauterising wounds

A

Treating skin conditions like acne scars they can burn off the top layers of scarred skin

51
Q

What can optical fibres carry

A

Visible light over long distances

52
Q

In an endoscope where can the image be seen

A

Through an eyepiece or displayed as a full colour moving image on a screen

53
Q

In a symmetrical shape hoe do you find the centre of mass

A

The lines of symmetry

54
Q

How do generators work

A

Turning a magnet end to end in a coil to create a current that lasts as long as YOY spin the magnet

55
Q

What do step up transformers do

A

Step the voltage up

56
Q

What do step down transformers do

A

Step the voltages down

57
Q

What is a load in a switch mode transformer

A

The thing you’re charging or powering

58
Q

Why are switch mode transformers good

A

Efficient.

They use little power when they’re switch on and no load is applied e.g no phone in phone charger