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100 Cards in this Set

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  • Back
An Atom consists of...
a small positively charged nucleus surrounded by negatively charged electrons
All electrostatic effects are due to...
the movement of electrons
When a polythene rod is rubbed with a duster...
When an acetate rod is rubbed with a duster...
The rod becomes negatively charged
The rod becomes positively charged
Electric shocks can be avoided by...
connecting an earth wire to items that could become charged, standing on an insulating mat, wearing shoes with insulated soles, or using anti-static sprays/liquids/cloths
A dust precipitator works by:
There is a grid that is charged at the bottom of the chimney, and on both sides of the chimney two plates with the opposite charge to the grid. As dust passes the grid it takes on that charge, and is then attracted to the plates. At regular intervals the plates vibrate and the dust drops onto a collector.
Paint spraying using electricity works by:
The spray gun is charged, and the bike given the opposite charge. As the paint passes the nozzle, it is given the same charge as the gun, and the particles repel each other and spread out for an even spray. The particles are then attracted to the bike so they stick to it.
power=
voltage x current
resistance=
voltage/current
A... changes the resistance
variable resistor/rheostat
If the resistance is fixed, as voltage increases...
current increases
If the power supply is fixed, as resistance increases...
current decreases
The live wire...
The neutral wire...
The earth wire...
carries the voltage round the house
completes the circuit, providing a return path
is connected to ground the appliance in case of the item becoming live
Resistance is measured in...
Ohms
Ultrasound is at...
20,000Hz
In a longitudinal wave:
Regions of higher pressure:
Regions of lower pressure:
Compressions
Rarefactions
In a longitudinal wave the vibrations of the particles are...
parallel to the wave
In a transverse wave, the vibrations of the particles are...
at right angles to the wave
When an ultrasound is used to break down kidney stones...
The beam is directed at the stone, the stones break down into smaller pieces, and are then excreted
Ultrasound is used instead of x-ray because
it can produce images of soft tissues and doesn't damage living cells
Ultrasound can be used for full body scans because
when it is reflected from surfaces in the body, the time that it takes to travel back is recorded, and by the time it takes it to get back and the amount of the wave absorbed a picture can be built up of the type of tissues and their depth
Nuclear radiation causes... by...
ionisation, removing or gaining electrons from atoms
The half-life of a radioisotope is...
The time it takes for half of it to decay
The three types of radiation are...
Alpha, beta, gamma
Nuclear equation for alpha decay...
238 234 4
U -> Th + He
92 90 2
Nuclear equation for beta decay...
14 14 0
C -> N + e
6 7 -1
When gamma is given out, how does the element decay?
It doesn't. Gamma is an energy wave.
Background radiation comes from...
Rocks
Space
Radioactive waste
Hospitals
Radiation is used in...
Smoke alarms
Medical/Leak tracers
Dating rocks
Carbon Dating
Cobalt-60 is used to...
treat cancer
X-rays are made by firing...
high speed electrons at tungsten targets
Radiation is used medically to...
Kill tumours, as tracers
In a nuclear power station...
uranisum-235 is bombarded with neutrons until it splits, reducing more neutrons that could strike the nucleus of other atoms, causing a chain reaction. This releases a large amount of energy. Boron control rods are used to absorb excess neutrons if the reaction gets too violent. A graphite moderator also is used to slow down the neutrons.
Nuclear fusion is...
two light nuclei fusing together releasing heat energy.
Safely replicating fusion on earth has not yet been possible.
Gravity is...
the force of attraction between every object
Any object moving in a circle needs a ... this is called...
force towards the centre of the circle, centripetal force
Gravitational forces obey an
inverse square law
time=
distance/speed= (2pir)xspeed
A polar satellite orbits...
100-20km above earth
A geostationary satellite orbits
above the equator
A scalar quantity has..., while vectors have... and...
magnitude, magnitude and direction
s
u
v
a
t
Distance
Initial velocity
Final velocity
Acceleration
Time
Gravity causes an acceleration of...
10metres per second per second
When a ball is thrown... speed is constant
horizontal
Newton's third law is...
Every action has an equal and opposite reaction
Momentum=
mass x velocity
force=
change of rate of momentum
Microwave signals are sent into space from a
parabolic transmitter
The ionosphere reflects frequencies below...
30Mhz
Geostationary sattelites orbit...
36,000 kilometres above the equator
The smaller the gap, the...
greater the diffraction
Television aerials must have... with the transmitter
line of sight
Interference is caused by...
a crest and trough from two waves hitting each other and cancelling each other out
Constructive interference...
The waves meet in phase
Destructive interference...
The waves meet out of phase
Unpolarised light=
Polarised light=
Many planes of oscillation
One plane of oscillation
refractive index=
Speed of light in vacuum/speed if light in medium
Optical fibres rely on...
total internal reflection
The critical angle is the...
angle of incidence in the more dense medium that produces an angle of refraction of 90 degrees in the less dense medium.
A parallel beam of light from a distant object can be converged to a focus in the...
focal plane
magnification=
image size/object size
An image made by a magnifying glass is a... and cannot be... because...
virtual image, projected onto a screen, no light passes through it
resistance=
voltage x current
The higher the resistance, the
lower the current
A variable resistor works by...
Changing the length of wire in a circuit, the more wire, the more resistance
When electrons collide with the atoms in a filament bulb,
The atoms vibrate more, leading to increased collision, temperature and resistance
V out =
R
2
-------------- V
R + R 2
1 2
The resistance of a thermistor increases with...
The resistance of a LDR increases with...
lack of temperature
less light
In a transistor, a small base current can...
switch on a greater current through the collector
Two transistors combined can make an....
AND gate
An AND gate requires...
Both inputs on.
A NAND gate requires...
Neither inputs on
An OR gate requires...
Either input on.
A NOT gate requires...
No input
A NOR gate requires...
Both inputs off.
A relay works...
like a switch, but switches between normally open contacts (NO) and normally closed contacts (NC)
The direction of a field around a wire can be found using...
the right hand grip rule
When a wire is placed between two magnets, it moves out of the gap when...
the current is turned on
To predict the direction a motor turns, you use...
Flemings left hand rule
To make a motor turn faster,
the number of turns on the coil is increased, the size of the current is increased or the strength of the magnetic field is increased
The direction of the current in a motor is reversed... This is to make sure...
every half turn, the force is always in the same direction
The job of the commutator is...
to make the motor continue to spin
A... increases the force on the coil and keeps it constant as the motor turns
radial field
When a wire is moved between... a ...is induced and...
If the wire is moved downwards, the... is reversed and the... is in the opposite direction.
two poles of a magnet, voltage, current passes
voltage current
The voltage generated in a wire depends on...
the speed it moves in between the poles of a magnet
Increasing the speed of rotation of the electromagnet in a power plant increases...
the current induced and the frequency of the voltage
Increasing the number of turns in the electromagnet on a generator...
increases the magnetic field and the voltage
Slip rings are connected to the ends of the coil to allow...
the coil to spin without winding the wire around itself
Brushes are...
contacts that touch the slip rings and complete the circuit
A transformer consists of...
The input AC is connected to... and the output AC is obtained from...
two coils of wire wrapped round an iron core
primary coil
secondary coil
Step down transformers have...
Step up transformers have...
more turns on the primary coil
more turns on the secondary coil
voltage across the primary
------------------------------------------- =
voltage across the secondary
number of turns on the primary coil
--------------------------------------------------------
number of turns on the secondary coil
power loss=
2
current x resistance
Diodes need an input of around...
0.6V before they start to work
A diode consists of...
a piece of n-type and p-type semiconductor joined together
N-type semiconductor has...
P-type semiconductor has...
The junction between the two has...
an excess of electrons
a lack of electrons ( the gaps where they should be are called holes)
None of either
A diode only allows...
current to pass one way
If the positive terminal is connected to the n-type...
If the positive terminal is connected to the p-type...
The junction widens and no current passes
The junction narrows until it disappears and current passes
A bridge circuit consists of...
four diodes
A capacitor stores...
electrical energy
To make the output of a bridge circuit smoother...
a capacitator can be added