Physics Revision Notes

My notes for my mock. Hoping for an A*

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  • Created on: 10-01-11 17:53
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IGCSE Physics-Revision
Heat
Temperature: measurement of hotness of a body. Measured in Kelvin or Celsius.
Thermal capacity (s.h.c): The heat energy needed to raise the body by one degree (Units J°C¯¹)
To find the amount of heat to raise a body: H=m x c (-)
E.g. How much heat is needed to raise 0.75kg of water from 20°C to 100°C?
H=mc(-)
H=0.75x4200x(100-20)
H=252000J
H=252KJ
Factors which affect temperature rise:
a) The material (whether it is wood or metal etc.)
b) The mass of the material being heated
c) The heat energy supplied
Specific latent heat: the amount of heat energy needed to arrange the bond structure
Specific latent heat of fusion (unit JKg¯¹):H=m x l (needed for melting substances)
Specific latent heat of vaporisation (unit J):H=m x l(needed for boiling substances)
Evaporation: the change of state from a liquid to a gas. This process occurs at all temperatures
Rate of evaporation can be increased by:
a) A large surface area
b) A hot or cold air blowing over the liquid
c) Higher temperatures
The three types of Heat transfer
a) Conduction- occurs in liquids solids and gases and travel from high heat to low heat due to
the kinetic energy. Solids conduct the best
b) Convection- occurs in liquids and gases and travels from high to a low
heat. It normally rises up through the fluid due to the expansion of
molecules. Moves in a circular motion
c) Radiation- the transfer of energy through electromagnetic waves. Best
example is the heat radiation from the sun in which heats the earth

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Forces and motion
Force is something that tries to change the shape, speed and direction of an object
UNITS: Newtons
Shown as a diagram of a proportional arrow
Generally: Force=mass x acceleration (Newton's 2nd law)
So: acceleration= force ÷ mass
Work is how much energy was used in the movement of an object from A to B
Work done= force x distance moved (work is in Joules)
Power is the rate at which work done is carried out
Power= work done ÷ time taken (power…read more

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Liquid pressure=height x density x gravity
Circuits
A battery is a source of electric current
Ammeter to measure flow of current Volt metre to measure energy change
Current is the flow of electrical charge. The charge is measures in coulombs
Q=It (Charge=current x time)
Electromotive force (E.M.F) - This is the amount of energy given to a charge when is passes
through an electrical source (such as a battery or power supply)
E
E.M.F= energy ÷ charge V = Q (E.M.F=Volts-V/energy=joules-J
/charge=coulombs-C)
Potential difference (P.D.…read more

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R=1/R1+1/R2+1/R3 Then use V=IR to find current in b
The potential divider- this is the output voltage in a section of a linear circuit.
(Vin=power supply/Vout=potential divider)
R1=7
R2=6
Vin=12
V (out) V (in)×6
R2) V (out) =
R2
V (in) = (R1+ 13
V (out) = 72
13 = 5.54V
With the use of a potential divider, you can then find
the amount of POWER which leaves the circuit.…read more

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Wave Motion
A wave is a movement of a DISTURBANCE through a source, such as water...
This movement is a transfer of energy from a source to a surrounding area...
Waves can be split into two groups...
Mechanical Waves Electromagnetic Waves
Water Radio
Sound Radar
Waves on springs Infra-red
Waves on stretched strings Light
Seismic waves Ultra-violet
x-ray
gamma ray
The wave equation: This is used to find the VELOCITY of the wave.…read more

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Transverse and longitudinal waves
Transverse wave ­ all the particles vibrate at a right angle to the direction. Each particle is slightly
out of step with the next. There is no overall movement
Eg, Water waves
Longitudinal waves ­ all particles vibrate in the same direction of which the wave is travelling in.
Each particle is slightly out of step with the next. There is no other movement in any direction.…read more

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Electronics
The diode ­ this is a rectifier which works on half
wave rectification.
A full-wave rectifier ­ this converts an AC to a DC
A light dependant resistor (L.D.R) ­ this uses light to determine the amount of resistance
As light intensity increases, the resistance decreases.…read more

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Magnetic fields due to electric currents
A single wire with a current will give off a magnetic field
A solenoid is a coil which is wound on a cylinder. It
has a magnetic field like a bar magnet but the field
flows inside the solenoid.
Fleming's left hand rule will help with predicting the force or
motion of the wire. This is applied for the motor affect.…read more

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Fleming's right hand rule is used to find induction in a straight wire
EQUATIONS FOR
RESITORS
1.…read more

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