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Useful Formulas for the IGCSE Physical Science Examinations
General Physics
Formula in SymbolsFormula in Words
v = d / tspeed = total distance / total time
w = m x gweight = mass x acceleration of gravity
a = v / tacceleration = change in speed / change in time
d = m / vdensity = mass / volume
F = m x aforce = mass x acceleration
x = k x Fextension = a constant x load
W = F x dwork = force x distance
p.e. = m x g x hpotential energy = mass x acceleration of gravity x height
k.e. = ½ x m x v2kinetic energy = ½ x mass x velocity squared
e = Eout / Ein x 100%energy efficiency = energy output / energy input x 100%
E = Wenergy used = work done
E = m x c2energy of a nuclear reaction = mass x speed of light squared
P = E / tpower = energy / time
Physics of Waves
Formula in SymbolsFormula in Words
c = f x speed of a wave = frequency x wavelength
i = rangle of incidence = angle of reflection
n = sin i / sin rindex of refraction = sine of incident angle / sine of refracted angle
Electricity and Magnetism
Formula in SymbolsFormula in Words
I = Q / tcurrent = charge / time
R = V / Iresistance = potential difference / current
R = k x l / Aresistance = a constant x length / cross sectional area
R = R1 + R2resistances in series add together
1 / R = 1 / R1 + 1 / R2reciprocals of resistances in parallel add together
I = I1 + I2currents in parallel add together
Iin = Iouttotal current into a point = total current out of a point
V = V1 + V2voltage of source = sum of all voltage drops in a circuit
P = I x Vpower used in an electric circuit = current x voltage
E = I x V x tenergy used in an electric circuit = current x voltage x time
Vp = Npvoltage in primary coil = number of turns in primary coil
Vs = Nsvoltage in secondary coil number of turns in secondary coil
Vp x Ip = Vs x Ispower in primary coil = power in secondary coil (for a perfect transformer)
Geometry
Formula in SymbolsFormula in Words
a = s2area of a square = length of side squared
a = l x warea of a rectangle = length x width
a = ½ x b x harea of a triangle = ½ x base x height
a = x r2area of a circle = Pi x radius squared
v = s3volume of cube = length of side cubed
v = l x w x hvolume of cuboid = length x width x height
v = x r2 x hvolume of cylinder = Pi x radius squared x height
You should be able to solve equations with three variables for any variable.
For example, if a = b x c, then b = a / c and c = a / b.
Formulas in bold are for core. Other formulas are extended, but they also help for many core questions.
General Physics
Formula in SymbolsFormula in Words
v = d / tspeed = total distance / total time
w = m x gweight = mass x acceleration of gravity
a = v / tacceleration = change in speed / change in time
d = m / vdensity = mass / volume
F = m x aforce = mass x acceleration
x = k x Fextension = a constant x load
W = F x dwork = force x distance
p.e. = m x g x hpotential energy = mass x acceleration of gravity x height
k.e. = ½ x m x v2kinetic energy = ½ x mass x velocity squared
e = Eout / Ein x 100%energy efficiency = energy output / energy input x 100%
E = Wenergy used = work done
E = m x c2energy of a nuclear reaction = mass x speed of light squared
P = E / tpower = energy / time
Physics of Waves
Formula in SymbolsFormula in Words
c = f x speed of a wave = frequency x wavelength
i = rangle of incidence = angle of reflection
n = sin i / sin rindex of refraction = sine of incident angle / sine of refracted angle
Electricity and Magnetism
Formula in SymbolsFormula in Words
I = Q / tcurrent = charge / time
R = V / Iresistance = potential difference / current
R = k x l / Aresistance = a constant x length / cross sectional area
R = R1 + R2resistances in series add together
1 / R = 1 / R1 + 1 / R2reciprocals of resistances in parallel add together
I = I1 + I2currents in parallel add together
Iin = Iouttotal current into a point = total current out of a point
V = V1 + V2voltage of source = sum of all voltage drops in a circuit
P = I x Vpower used in an electric circuit = current x voltage
E = I x V x tenergy used in an electric circuit = current x voltage x time
Vp = Npvoltage in primary coil = number of turns in primary coil
Vs = Nsvoltage in secondary coil number of turns in secondary coil
Vp x Ip = Vs x Ispower in primary coil = power in secondary coil (for a perfect transformer)
Geometry
Formula in SymbolsFormula in Words
a = s2area of a square = length of side squared
a = l x warea of a rectangle = length x width
a = ½ x b x harea of a triangle = ½ x base x height
a = x r2area of a circle = Pi x radius squared
v = s3volume of cube = length of side cubed
v = l x w x hvolume of cuboid = length x width x height
v = x r2 x hvolume of cylinder = Pi x radius squared x height
You should be able to solve equations with three variables for any variable.
For example, if a = b x c, then b = a / c and c = a / b.
Formulas in bold are for core. Other formulas are extended, but they also help for many core questions.
