Formulae Flashcards
Current (amperes)
Current (amperes) = charge (coulombs) passing a point per second.
I = Q/T
Rearrange the formula I = Q/t (electric current) so that Q (charge) is the subject.
Q= I × t
Resistance at constant temperature
Resistance (Ohms) = potential difference (Volts)/current (Amperes)
R = V/I
Power in a circuit
Power (watts) = potential difference (volts) × current (amperes).
Power = VI
Energy transformed in a circuit
Energy = power × time so:
Energy transformed in a circuit = potential difference (V) × current (A) × time (s)
E = VIt
Distance =
Distance = rate × time
D = rt
Density =
Density = mass divided by volume
D= m/v
Average speed =
Average speed = distance moved divided by time taken
avg speed = distance/ time
Relative density =
Relative density = density of substance/density of water
Average acceleration =
Average acceleration = change in velocity/time taken
Slope =
rise/run
Pressure=
weight/area
At depth h in liquid of density d:
pressure = pgh
Work done =
force × distance
1 volt =
1 J/C
1 Joule per Coulomb
What is the equation for the momentum of an object?
mass × velocity
Force linked to change in momentum
F=(mv-mu)/t
Force = change in momentum / time taken
Pressure and volume in a gas
PV = constant
Pressure × volume = constant
Kinetic energy (KE) =
KE = 1/2mv²
Refractive index=
Refractive index= speed of light in air/speed of light in medium
Critical angle
sin c = 1/n
c= critical angle n= refractive index (of medium)
Electrical power
P = IV
I = current V = e.m.f or voltage
The equation linking force, mass and acceleration
F= m×a
Boyle’s law (compressing gases)
p1v1 = p2v2
Wave equation
speed = frequency × wavelength
Refractive index
Speed of light in vacuum ÷ speed of light in medium
or
Sin i ÷ sin r
