Extras Flashcards
What do simple levers make it easier to do
Easier to do work by moving the distance the force is applied further from the pivot
Where are pendulums used
Clocks, playground swings, fairground rides
What is cross section area in a hydraulic measured in
M^2
What is velocity
Both the speed and direction of an object
Example of a centripetal force using friction
A car going round a bend.
Friction between the cars tyres and the road
What can magnetic fields be represented by
Field diagrams - the arrows on them always pint from North Pole to the South Pole
What is a magnetic field made up of
Concentrated circles with the wire in the centre
How to work out which way the magnetic field is going around a wire
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
How can you increase the strength of the magnetic field around a coil of wire (a solenoid)
Adding a magnetically soft iron core through the middle of the coil (an electromagnet is formed)
What are electromagnets used in
Electric bells, car ignition circuits and some security doors
What way does current flow usually
From +ve to -ve
What does electric motors use the motor effect for
To get them and keep them moving
How do electric motors help make CD players, food mixers, fan heaters, fans, printers, drills, hair dryers, cement mixers work
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.
Why will a freely suspended object swing until it’s centre of mass is vertically below the point of suspension
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.
What is the wiring to a three pun plug
- 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
Why are parts of the plug made of metal like copper and brass
Because they are good conductors
What are two important effects of gravity
Gives everything a weight
Makes everything accelerate towards the ground
What is weight measured using
A sprint balance or Newton metre as its in newtons
What is mass measured using
A mass balance as its in Kg
What is the gravity on the moon
1.6 N/kg
What is an example of a circuit breaker
Residual current circuit breaker
RCCB
How do RCCBs operate
Detecting a different in he current between the live and neutral wire
If an appliance is double insulated what does this mean
It has no earth wire connection - only metal cased ones do
What is extension of a spring measured by
Metres
What is the limit of proportionality
The maximum force an elastic object can take and still extend proportionately
What is momentum
The property of moving objects
What is a closed system
No external forces are acting on it
What is the conservation of momentum
The total momentum before is the total momentum after
How do u find velocity in the momentum
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
What does aerodynamic mean
They are shaped in such a way that air flows very easily and smoothly past them
If the resistance in a component increases what happens to the current
The smaller the current that flows
By varying the variable resistor what happens
It alters the current letting you take several pairs of readings from the A and V
What is a diode made of and what is it used for
Semiconductor material such as silicon and to regulate the potential difference. Useful in electronic circuits
Why are led used a lot
They use a smaller current than other forms of lighting
Where are thermistors used
Car engine temperature sensors, electronic thermostats
How to work out current in a series circuit
Total voltage divided by resistance
What is electric current
The movement of charge carriers
What does the gain dial control
How many volts each centimetre division represents on the vertical axis
What does the time base dial control
How many milliseconds each division represents on the horizontal axis
When do cuss ratings needed for cables increase
With cable thickness
What are cables known as that only carry the live and neutral wire
Two core cables
How do filament bulbs work
Passing a current through a very thin wire heating it up so it glows
How to work out power rating of appliances
Energy transferred divided by time
What experiment did Rutherford and marsden do
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.
What is half life
The average time it takes for half the number bed of nuclei in a radioactive isotope sample to halve
What is radiotherapy
Treatment of cancer using gamma rays
How can X-ray images be formed electronically
Using charged coupled devices (CCDs)
How do CCDs work
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
When working out the power of the two lenses which was is negative and which is positive
Negative is diverging
Positive is converging
What are lasers used to treat besides eyes and cauterising wounds
Treating skin conditions like acne scars they can burn off the top layers of scarred skin
What can optical fibres carry
Visible light over long distances
In an endoscope where can the image be seen
Through an eyepiece or displayed as a full colour moving image on a screen
In a symmetrical shape hoe do you find the centre of mass
The lines of symmetry
How do generators work
Turning a magnet end to end in a coil to create a current that lasts as long as YOY spin the magnet
What do step up transformers do
Step the voltage up
What do step down transformers do
Step the voltages down
What is a load in a switch mode transformer
The thing you’re charging or powering
Why are switch mode transformers good
Efficient.
They use little power when they’re switch on and no load is applied e.g no phone in phone charger
