Pysics Equations

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Reflection of Light from Spherical Mirrors

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Reflection of light in a spherical convex mirror.

Formula	Abbreviations	Mnemonic
$\frac{1}{u} + \frac{1}{v} = \frac{1}{f}$	u - distance from the object to the mirror v - distance from the image to the mirror f - focal length nb, v is + for real image v is - for virtual image f is + for concave mirror f is - for convex mirror
$m = \frac{v}{u}$	m - magnification u - distance from the object to the mirror v - distance from the image to the mirror	over under

Refraction

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Refraction in a Perspex (acrylic) block.

Formula	Abbreviations	Mnemonic
$\frac{Sin(i)}{Sin(r)} = n$	i - Angle of incidence r - Angle of refraction n - Refractive Index between the two media	Being rare gets presidence over being dense
$_xn_y = \frac{1}{_yn_x}$	For any two media x and y n - Refractive index between the two media
$n = \frac\mbox{Real depth}\mbox{Apparent depth}$	n - Refractive Index of medium	Real truth presides over apparent truth anyday
$n = \frac\mbox{Speed of light in vacuum}\mbox{Speed of light in medium}$	n - Refractive Index of medium	The vacuum is always lighter, so it rises to the top
$n = \frac{1}{Sin(C)}$	n - Refractive Index C - Critical angle

Lenses

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Convex lens in action

Formula	Abbreviations	Mnemonic
$\frac{1}{u} + \frac{1}{v} = \frac{1}{f}$	u - distance from object to lens v - distance from image to lens f - focal length where: u is always + v is + for a real image v is - for a virtual image f is + for a convex lens f is - for a concave lens
$m = \frac{v}{u}$	m - magnification v - distance from image to lens u - distance from object to lens
$P = \frac{1}{f}$	P - power of lens f - focal length	power of lens is measured in per metres
$P = P_1 + P_2$	P - overall power of combination of lenses P₁ - power of first lens P₂ - power of second lens
$\frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2}$	f - overall focal length of combination of lenses f₁ - focal length of first lens f₂ - focal length of second lens where: f is given a + for a convex lens and a - for a concave lens.

Temperature

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Formula	Abbreviations	Mnemonic
t(C) = t(K) - 273.15	t(C) - temperature in degrees Celsius t(K) - temperature in degrees Kelvin	To serve three-period, single fights. Small number = Big number - a lot.

Quantity of Heat and Heat Transfer

Formula	Abbreviations	Mnemonic
$Q = mc\Delta \Theta$	Q - heat energy m - mass (kg) c - specific heat capacity $\Delta \Theta$ - change in temperature	MCAT
$Q = ml$	Q - heat energy m - mass (kg) l - specific latent heat

Waves and Wave Motion

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Surface waves in water

Formula	Abbreviations	Mnemonic
$T = \frac{1}{f}$	T - time for one cycle to pass a point f - frequency (hz) or cycle per second
$c = f \lambda$	c - velocity of wave f - frequency $\lambda$ - wavelength
$f' = \frac{fc}{c-u}$	f' - observed frequency f - actual frequency c - speed of wave in the medium u - speed of source nb. u is negative if source is moving away from observer.

Vibrations and Sound

Formula	Abbreviations	Mnemonic
$I = \frac{P}{A}$	I - sound intensity P - power A - area	Patrick's over-Aim is an Intense miss
$2lf = \sqrt{\frac{T}{\mu}}$	f - fundamental frequency l - length $\mu$ - mass per unit length T - tension	2 Live freely is the root of tears undue.
$n^{th}$ overtone = $(n+1)^{th}$ harmonic	n - any number
c = 4f (l + 0.3 d)	c - speed of sound in medium </br> f - frequency of note emitted </br> l - length of closed pipe </br> d - diameter of pipe

Static Electricity

Formula	Abbreviations	Mnemonic
$F=\frac {Q_1Q_2}{4\pi \varepsilon d^2}$	Q1 and Q2 = charges F = force between charges d = distance between charges	Queens over four pies eating a square dinner = very forceful.
$\varepsilon = \varepsilon _r \varepsilon _0$	E = Permittivity of medium Er = Relative permittivity of medium Eo = Permittivity of a vacuum
$E = \frac{F}{Q}$	E = Electric Field Strength F = Force Q = Charge	'Free and easy but queasy' triangle

Potential Difference and Capacitance

Formula	Abbreviations	Mnemonic
W = QV	W = Work Done </br> Q = Charge/Number of Coulombs Transferred </br> V = Potential / Voltage	Where is the Queen's Vulture?
$C=\frac{Q}{V}$	C = Capacitance of a conductor </br> Q = Charge </br> V = Potential / Voltage	'Queens Catch Vultures' Triangle
$Cd= \varepsilon A$	C = Capacitance of a conductor </br> d = Distance between plates </br> E = Permittivity of the dielectric </br> A = Area of overlap of the plates
$W= \frac{1}{2} C V^2$	W = Energy stored in a charged capacitor </br> C = Capacitance of a conductor </br> V = Potential / Voltage </br> nb. This formula gives the average work done </br> It can not be derived by combining W=VQ with Q=VC.	Similar to $W= \frac{1}{2}mv^2$ in log tables.

Current and Charge

Formula	Abbreviations	Mnemonic
Q = It	Q = Charge gone past </br> I = Steady current </br> t = time	Looks like "quit".

Electromotive Force and Potential Difference

Formula	Abbreviations	Mnemonic
W = QV	W = Energy given out</br> Q = Charge gone past</br> V = Potential / Voltage	Where is the Queen's Vulture?
VI=P	V = Potential difference between two points</br> I = Current flowing between two points </br> P = Power dissipated between two points.	Very Important Person

Resistance, Current, Voltage

Formula	Abbreviations	Mnemonic
$R = \frac{V}{I}$	R = Resistance </br> V = Potential / Voltage </br> I = Current	Ronaldo is Very over Inphasised.
$\rho l = RA$	p = Resistivity of the material in the conductor </br> R = Resistance </br> A = Cross-sectional area </br> l = Length	Pink Light is Readily Accepted
$4\rho l = R \pi d^2$	l = Length </br> p = Resistivity of the material </br> d = Diameter of wire </br> R = Resistance	4 Pirate Leaders are Raiding Pies at the square Dance
When a wheatstone bridge is balanced: </br> $R_1 R_4 = R_2 R_3$
$P=I^2 R$	P = Power </br> I = Current </br> R = Resistance
$I_{rms} = \frac{I_0}{\sqrt{2}}$

Series Circuit

Formula	Abbreviations	Mnemonic
$R =R_1 + R_2 + R_3$	R = Total resistance </br> R1, R2 and R3 are separate resistors in series
$A_1 = A_2 = A_3$	A1, A2 and A3 are three ammeters in series
$V = V_1 + V_2 + V_3$	V = Total voltage </br> V1, V2 and V3 are three batteries in series

Parallel Circuit

Formula	Abbreviations	Mnemonic
$\frac{1}{R} = \frac{1}{R_1} + \frac{1}{R_2} + \frac{1}{R_3}$	R = Total resistance </br> R1, R2 and R3 are separate resistors in parallel
$A= A_1 + A_2 + A_3$	A1, A2 and A3 are three ammeters in parallel
$V_1 = V_2 = V_3$	V1, V2 and V3 are three batteries in parallel

Effects of an Electric Current

Formula	Abbreviations	Mnemonic
$W=I^2 Rt$	W = Heat given out by a wire </br> I = Current </br> R = Resistance </br> t = Time

Speed, Displacement and Velocity

Formula	Abbreviations	Mnemonic
$v= \frac{s}{t}$	v = Average velocity</br> s = Displacement </br> t = Time taken

Acceleration

Formula	Abbreviations	Mnemonic
$a= \frac{v-u}{t}$	a = Average accleration</br> v = Final velocity </br> u = Initial velocity</br> t = Time taken
$v=u+at$	a = Average accleration</br> v = Final velocity </br> u = Initial velocity</br> t = Time taken	Given in log tables
$s=ut+ \frac{1}{2}at^2$	a = Average accleration</br> s = Displacement</br> u = Initial velocity</br> t = Time taken	Given in log tables
$v^2 = u^2 +2as$	v = Final velocity </br> u = Initial velocity </br> a = Average acceleration </br> s = Displacement	Given in log tables

Force, Mass and Momentum

Formula	Abbreviations	Mnemonic
F = ma	F = Force </br> m = Mass </br> a = Acceleration
p = mv	p = Momentum </br> m = Mass </br> v = Velocity
$F= \frac{mv-mu}{t}$	F = Force </br> m = Mass </br> v = Final velocity </br> u = Initial velocity </br> t = Time
$m_1 u_1 + m_2 u_2 = m_1 v_1 + m_2 v_2$	m1 = Mass of object 1 </br> u1 = Initial speed of object 1 </br> v1 = Final speed of object 1 </br> m2 = Mass of object 2 </br> u2 = Initial speed of object 2 </br> v2 = Final speed of object 2 </br>

Pressure and Gravity

Formula	Abbreviations	Mnemonic
$Density= \frac{Mass}{Volume}$ </br> i.e. $\rho = \frac{m}{v}$	p = Density </br> m = Mass </br> v = Volume	"Monkeys Drink Vodka" Triangle
$P = \frac{F}{A}$	P = Pressure </br> F = Force </br> A = Area
P = pgh	P = Pressure </br> p = Density </br> g = Gravity </br> h = Depth (height)

Magnetic Fields

Formula	Abbreviations	Mnemonic
$F=BIl$	F = Force </br> B = Flux density of field </br> I = Current in conductor </br> L = Length of conductor	Bills are forceful
$F = qvB$	F = Force on particle </br> q = Charge on particle </br> v = Speed of particle </br> B = Flux density of field
$\Phi = BA$	$\Phi$ = Magnetic Flux </br> B = Magnetic Flux Density </br> A = Area	$1 Wb = 1 Tm^2$
$E=-\frac{d\Phi}{dt}$	Induced emf E = (Final flux - Initial flux) / (Time taken)