# P2 and P3

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• Created by: jp3louis
• Created on: 16-06-16 18:57
P2: What is the unit for resultant force?
Newtons
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P2: what is the unit for mass
KG
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P2: What is the unit of acceleration?
m/s squared.
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P2: What is the unit of final velocity?
m/s
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P2: What is the unit of initial velocity?
m/s
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P2: What is the unit of weight
newtons
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P2: What is the unit of gravitational field strength
10 N/Kg
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P2: What is the unit of force
Newtons
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P2: What is the unit of spring constant
N/m
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P2: What is the unit of extension
Meters.
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P2: What is the unit of work done
Joules
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P2: What is the unit of power
watts
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P2: What is the unit of change in gravitational potential energy
Joules.
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P2: What is the unit of momentum
kg m/s
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P2: what is current measured in?
A
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What is charge measured in?
C
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What is work done?
When a force causes an object to move through a distance is what we call work done.
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What is transferred when work is done?
Energy
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What happens when insulated materials are rubbed against eachother? What happens to the electrons?
They become electrically charged. Negative chraged electrons are rubbed off one material and onto the other.
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If a material gains electrons, what charge does it have? What happens if this is the other way round?
The material that gains electrons is negatively charged whereas the material that loses electrons is left with an equal positive charge.
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What is the electric current.
Its a flow of electrical flow.
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What is the symbols for all of these: open/closed switch, cell , battery, diode, resistor, variable resistor, lamp, fuse, voltmeter, ammeter, thermistor,ldr,LED
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Explain what a graph would look like when a current goes through a resistor at a constant temperature?
Graph one on P2 30 questions. It is directly proportional to the potential difference across the resistor.
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What is resistance measured in?
OHMS.
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Explain what a graph would look like when the resistnace of the filament bulb increases.
Graph 2 on P2 30 questions. The resistance of a filament bulb increases as the temperature of the filament increases.
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Explain the graph when a current goes through a diode.
P2 3o questions number 3. The current through a diode flows in one direction only. The diode has a very high resistance in the reverse direction.
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Why do we use LED?
They are smaller.
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An LED emmits light at which point in a circuit?
WHen a current flows through it in the forward direction.
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The resistance of a thermistor decreases when?
When the temperature increases.
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What is the mains electricity in the Uk
230 V
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What is in a plug?
the earth wire - yellow/green. neutral wire- blue and the live wire is brown. There is a fuse a cable grip and an insulated wire.
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What different fuses do we have?
3, 5 and 14
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If an electrical fault causes too much current, what happens?
The Circuit breaker or fuse melts/stops it.
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Some circuits are protected by what?
RCCB's
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when an electrical charge flows through a resistor, what happens?
The resistor gets hot.
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Where can background radiation come from?
Rocks, cosmic rays, man made like nuclear tests and hispitals
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what is an alpha particle made up?
2 atoms - a proton an a neutron
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What is a beta particle?
An electron
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What is a gamma ray?
a wave.
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What is the ionising power for all of the radiations?
Alpha is strong. Beta is weak and Gamma is very weak.
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What can block each of the radiations?
Paper for alpha, aluminium for beta and lead for gamma.
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Which two radiations are deflected by both electric and magentic fields?
Alpha, beta. Gamma isn't.
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What are the two fissionable substances used in nuclear reactors?
Uranium 235 and plutonium 239
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What is nuclear fission?
the splitting of an atomic nucleus. the uranium and plutonium absorb an atom and then the nuecleus splits.
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What is nuclear fusion?
Joining of two atomic nuclei to form a larger one. This is how energy is released in stars/
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Go through the star sequence.
Dust and gas is called a protostar. This turns into a main sequence star. This then splits into two - red giant which turns into a white dwarf then a black dwarf. A red super giant goes to a supernova and then to a neutron star/black hole.
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What are x rays absorbed by?
Metal and bone
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Give some ways x rays can be used.
bone fractures, dental, killing cancer cells.
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What happens during an ultrasound?
The waves are reflected when they meet a boundary between two different medias.
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Where can we use ultrasounds?
Pre-natal scanning and kidney stones.
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What shape is a converging lens and what does it do?
() causes rays of light to move together at the focal point (converge)
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What shape is a diverging lens and what does it do?
)( causes rays of light to diverge (spread out) used for short sighted.
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What is a magnifying glass made out of?
A converging lense as it moves the light together to make it bigger.
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What does the cornea do
Cornea- focusus
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What does the iris do?
Its the coloured part of the eye and it controls the size of the pupil which allows control over how much light you want in the eye.
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WHat does the lens do?
Changes shape to focus light from object at various distances. Its connected to the cillary muscles by the suspensery ligaments.
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What does the retina do?
Images are formed here.
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How can we send light among optical fibres?
Total internal reflection
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How do optical fibres work?
Bouning waves off the sides of a thin inner core of glass. The wave enters one end and is reflected unitl it gets to the other end.
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If the angle of incidence is less than the critical angle, what will happen in optical fibres?
Most of the light will pass out but a little is internally reflected.
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If the angle of incidence is equal to the critical angle, what will happen in optical fibres.
The emerging ray comes out along the surface and thers quite a bit of internal reflection.
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What is a force that when something is moved in a circle, tries to bring it back to the centre.
The centripetal force.
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What happens when current flows through a wire?
A magnetic field is produced around the wire.
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WHy is it important that ammeters have very low resistance?
So it affects the current as little as possible.
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## Other cards in this set

### Card 2

#### Front

P2: what is the unit for mass

KG

### Card 3

#### Front

P2: What is the unit of acceleration?

### Card 4

#### Front

P2: What is the unit of final velocity?

### Card 5

#### Front

P2: What is the unit of initial velocity?