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A level physics formulas > Everything > Flashcards

Everything Flashcards

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1
Q

4 kinematic formulas

A

v=u+at
v^2=u^2+2as
s=ut+1/2at^2
s=1/2(u+v)t

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2
Q

Fnet of falling bodies

A

Fnet=W-F

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3
Q

Formulas of force (both impulse and constant mass)

A

F=dp/dt
F=ma (constant mass)

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4
Q

Impulse

A

p=mv

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5
Q

Conservation of momentum

A

m1u = m1v1 + m2v2

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6
Q

Elastic collision

A

u1-u2=v2-v1
speed of approach=speed of separation

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7
Q

inelastic collision

A

m1v1 +m2u2 = (m1+m2)v

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8
Q

Moments

A

M=FxD
Clockwise moments= Anticlockwise moments

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9
Q

Hooke’s law

A

F=kx

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10
Q

Upthrust

A

U=pvg

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11
Q

Work done by force

A

WD=Fs cos θ

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12
Q

Work done ON gas

A

WD=-Pexternal (△v)

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13
Q

Work done BY gas

A

WD= Pexternal (△v)

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14
Q

Kinetic energy

A

KE=1/2mv^2

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15
Q

Gravitational potential energy

A

GPE=mgh

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16
Q

Elastic potential energy

A

EPE=1/2kx^2

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17
Q

Power

A

WD per unit time
P=Fv

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18
Q

Efficiency

A

useful WD/energy input x100%

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19
Q

Angular displacement θ

A

θ= s/r

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20
Q

Angular velocity ω

A

ω=dθ/dt
=2πf
=2π/T

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21
Q

Uniform circular motion v

A

v=rω

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22
Q

Centripetal acceleration Ac

A

Ac=v^2/r
=rω^2

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23
Q

Centripetal force Fc

A

Fc=mv^2/r
=mrω^2

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24
Q

Gravitational force of attraction between 2 masses

A

F= Gm1m2/r^2

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25
Q

(GRAV FIELD) Relationship between T and r?

A

T^2 ∝ r^3

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26
Q

Gravitational field strength g

A

g=Gm/r^2

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27
Q

Weight at poles of earth vs equator

A

At poles, W=N
At equator, Fc=W-N

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28
Q

Gravitational potential Φ

A

Φ=-Gm/r

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29
Q

Potential energy on mass in grav field

A

Ep=mΦ

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30
Q

Escape velocity and derivation

A

v=squareroot(2Gm/R)
derived from Ekinit=m△Φ

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31
Q

Energy needed for mass to reach infinity

A

TE=0

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32
Q

KE of orbiting mass

A

F between 2 masses= Fc
Gm1m2/r^2 = mv^2/r

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33
Q

Differences between in phase and out of phase? △Φ (phase diff)

A

in phase, △Φ=0
out of phase, △Φ=180 or π

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34
Q

Angular frequency θ

A

θ=2πf
=dθ/dt

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35
Q

Simple harmonic motion acceleration a

A

a=-ω^2x

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36
Q

Horizontal spring F

A

F=-kx

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37
Q

In a horizontal spring system what is ω?

A

ω=squareroot (K/m)
as a=-(K/m)x

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38
Q

In a pendulum, what is ω？

A

ω=squareroot (g/L)
as a=-(g/L)x

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39
Q

(graph) formulas for displacement, velocity and acceleration for Simple harmonic motion

A

x=x0 sin wt
v=wx0 cos wt
a=-w^2x0 sin wt

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40
Q

general velocity formula for SHM

A

±ω squareroot (x0^2-x^2)

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41
Q

KE of SHM displacement

A

KE=1/2mω^2 squareroot (x0^2-x^2)

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42
Q

PE of SHM displacement

A

PE=1/2mω^2 x^2

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43
Q

Graphical formula of PE energy-time graph

A

PE=1/2m(ω^2)(x^2)

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44
Q

Graphical formula of KE energy-time graph

A

KE=1/2m(ω^2)(x0^2-x^2)

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45
Q

Graphical formula of TE energy-time graph

A

TE=1/2m(ω^2)(x0^2)

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46
Q

Speed of EM waves

A

c=3.0 x 10^8

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47
Q

Intensity formula
and is proportional to??

A

I=Power/Area
I∝Amplitude^2

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48
Q

Power formula (intensity)

A

P= E/t

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49
Q

Malu’s Law (intensity/polarising)

A

I=I0 cos^2 θ
I∝cos^2 θ

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50
Q

Single slit diffraction formula

A

sin θ= λ/b
b is slit width

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51
Q

Rayleigh’s criterion (2 sources of light)

A

θ= λ/b =s/r
s is the dist between 2 sources
r is the dist between slit and source

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52
Q

Double slit

A

x= λD/a
x is fringe sep
a is slit sep
D is total dist from source to slit

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53
Q

Diffraction grating

A

d sin θ= n λ
d is slit sep
n is order

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54
Q

Fixed end vs free end (which one is in phase and which is antiphase)

A

Fixed end is in phase while free end is antiphase

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55
Q

Stationary waves 2 free end/fixed end formula for Length and frequency

A

L=n(λ/2)
F=n(V/2L)

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56
Q

Stationary waves 2 free end/fixed end formula for Length and frequency

A

L=n(λ/2)
F=n(V/2L)

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57
Q

Electric field strength E at a point in the field

A

E=F/Q
OR F=EQ

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58
Q

Electric field strength of uniformed field between charged parallel plates

A
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59
Q

Electric field strength of point charge in air

A
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60
Q

Electric force Fe

A

Fe= Eq

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61
Q

Coulomb’s law

A
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62
Q

Electric potential energy U
Positive and neg meaning

A

U=QV
Pos U: wd on field
Neg U: wd by field

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63
Q

Change in electric potential energy

A

△U=Q△V
=Q(Vf-Vi)

64
Q

Electric potential due to point/sphere charge

A

Same as electric field strength of point charge but instead of r^2 its just r this time

65
Q

Electrical potential energy of 2 isolated point charges

A
66
Q

Electric potential of multiple point charges

A

Vtotal=V1+V2+V3

67
Q

Electric potential energy of multiple point charges

A
68
Q

Steps to curve sketching for Resultant electric potential graph and resultant electric field strength graph

A
  1. Find magnitude of changes
  2. Find location of 0 field strength when E=0
  3. Find potential at zero field strength
  4. Find field strength at surface of spheres
69
Q

Graph eqn I of AC

A

I=I0 sinwt

70
Q

Why does heat dissipate in ac?

A
  • power dissipated in resistor
  • P proportionate to current square because P=I2R
    OR
  • ac current change direction every half cycle but direction is independent of current direction
71
Q

Finding RMS value in AC

A
  1. Square function/graph
  2. Average value
  3. Square root avg value in 2
72
Q

What is RMS value definition?

A

RMS of steady direct current dissipates thermal energy at the same avg rate as resistor as ac in a given resistor

73
Q

AC Formula of 《I> vs Irms difference?

A

area/T = average current squareroot (squared area/T) =Irms

74
Q

AC sinosoidal easier formula

A

Irms= I0/squareroot 2
Vrms=V0/squareroot 2

75
Q

Power of ac circuits

A

Pavg=Irms Vrms

76
Q

Pheat of AC

A

Pheat=I2Rcable

77
Q

Explain EMI and transformer input

A
  1. B field generation
  2. Change
  3. Flux linkage
  4. Faraday’s law
78
Q

Ideal transformer

A

Pinput=Poutput

79
Q

Graph eqn of V om AC （for ac-dc rectification)

A

Vac=V0 sin wt

80
Q

Equipotential lines definition

A

lines joining points in a field with same potential
ALWAYS meet electric field lines at right angles
(ie equipotential lines are perpendicular to electric field lines)

81
Q

What happens when charge is moved along an equipotential line

A

no work is done

82
Q

Relationship between electric field strength and electric potential

A

[MAG] electric field strength E is numerically equal to the electric potential gradient (dV/dr) at a point in the field

[DIR] neg sign shows direction of field strength, pointing to lower potential

83
Q

Electric potential gradient

A

dV/dr

only add negative for E=-dV/dr, where direction is needed

84
Q

Electric force using electric potential

A

F=-dqV/dr
=dU/dr

U=qV

85
Q

Unknown temp for thermometric property of empirical centigrade scale

A
86
Q

Absolute temp from celsius

A

K=C+273.15

87
Q

Celsius to absolute temp

A

C=K-273.15

88
Q

Ideal gas law for moles of gas

A

pV=nRT

89
Q

Ideal gas law for particles of gas

A

pV=NkT

90
Q

One mole

A

6.02 x 10^23
One mole of H atoms weigh 2g and 0.002kg

91
Q

Explain/prove pV=⅓Nm (basic idea)

A
  1. change in momentum
  2. N2L, F on 1 particle
  3. N3L F on wall opposite to F on gas particle
  4. Average F over area for MANY collisions from many particles in a random distribution
92
Q

Explain/prove pV=⅓Nm (LONG WORKING)

A
93
Q

KE of gas particles

A

=3/2 kT

KE directly prop to T

94
Q

Specific heat capacity C

A

c=Q/m△T
basically Q=mc△T

95
Q

Specific latent heat L

A

L=Q/m

96
Q

Internal energy of a gas U

A

U= KEsum + PEsum

97
Q

Internal energy of an ideal gas U

A

Uideal= KEsum + 0
because PEsum is 0

or Uideal = N
= 3/2 NkT =3/2nRT =3/2pV

98
Q

First law of thermodynamics

A

△Uincrease= Qto + Won

overall energy = heat + pressure

99
Q

WD on gas

A

WDon = -Pext△V

100
Q

Answering framework for thermodynamics and internal energy U

A

Microscopic vs Macroscopic

KE (temp)

PE (V, phase)

101
Q

WD on p-V graphs

A

Area under graphs

102
Q

p-1/V graph for isothermal?

A

linear graph of p=nRT(1/V)

103
Q

Magnetic flux Φ (FOR AREA)

A

Φ= Bperpendicular A
= (B cos θ) A
= BA cos θ

104
Q

Magnetic flux linkage (FOR SOLENOID COIL)

A

NΦ = N(BA)
= N(B cosθ)A
= NBA cosθ

105
Q

Induced electromag induction at a particular point

A

Einduced= -d(NΦ)/dt
= -d(NBA cosθ)/dt

106
Q

AVERAGE Induced electromag induction

A

Eave= △Φ/△t

107
Q

Layman EMI vs EM

A

EMI: Kinetic to electrical

EM: Electrical to Kinetic

108
Q

Explaining EMI induction framework

A
  1. Field
  2. Change/cut
  3. Linkage
    1. Faraday’s law
109
Q

Explaining eddy currents and damping

A
  1. Explain why emf is induced in the disc
  2. Explain why eddy currents are induced
  3. Explain why the disc comes to rest after a few oscillations
110
Q

Constant current I

A

I=Q/t
Q=It

111
Q

Current definition and d?/d?

A

rate of flow of charge
dQ/dt

112
Q

Drift velocity v for current carrying conductor

A

I =nAvq

113
Q

Proving drift velocity formula

A
114
Q

Potential difference pd

A

V=W/Q

115
Q

Power supplied by source

A

P =ItotalE
=Itotal^2Rtotal

116
Q

Power output of component

A

P=IdeviceV
=I^2Rdevice

117
Q

Resistance

A

R=V/I

118
Q

Resistance (the wire area etc)

A

R=pL/A

119
Q

Terminal pd (internal resistance)

A

Vt= E - Ir

120
Q

Efficiency

A

Eff= Pload/Psource
=I2Rload/I2Rtotal
=Rload/Rload+r

121
Q

How to increase efficiency?

A

minimise internal R of source
OR
maximise R of component

122
Q

Efficiency at max power

A

50% eff

123
Q

Maximum power transfer theorem

A

Rext same as Rint of EMF source

124
Q

Resistors in series

A

Reff= R1 + R2 + … +Rn

125
Q

Resistors in parallel

A

1/Reff = 1/R1 + 1/R2 + … + 1/Rn
OR
Reff= RaRb/Ra+Rb

126
Q

Potential divider rule

A

Vout/Vtotal = R/Rtotal

127
Q

Potentiometer circuit formula

A

Vtapped/Vtotal = Ltapped/Ltotal = Rtapped/Rtotal

128
Q

Balanced conditions of a potentiometer

A

VPJ=VQR
0=IPQ=IRJ
No current. Length of PJ is the balanced length

129
Q

Mag flux density of a long straight wire

A

B=µI/2πd

130
Q

Mag flux density of a flat circular coil

A

B=µNI/2r
N is no of turns PER UNIT LENGTH and NOT NO OF TURNS

131
Q

Mag flux density of a lomg solarnoid

A

B=µnI

132
Q

Mag force in a wire

A

F=BILsinθ

B is perpendicular!
F on 1 by 2= B2 I1 L1

133
Q

Mag force of charge particle

A

F= BQv sinθ
Bev sinθ for electron!

134
Q

F on charge moving in a circular field

A

equate Fb=Fc to get
Bqv sin 90=mv^2/r (find r)
or =mrw^2 (find T)

135
Q

Magnetic field into vs from paper

A

Into: clockwise
From: anti-clockwise

136
Q

Energy of 1 photon

A

E=hf
=hc/λ

137
Q

Relation of energy of photon and wavelength

A

Energy decrease when wavelength increase

138
Q

Photoelectric eqn

A

hf= Φ+½mvmax^2

139
Q

eV to joules

A

1eV=1.6 x 10^-19

140
Q

Threshold frequency

A

minimum freq for emission
hf=Φ
(basically the ½mv^2=0 and emitted e have no energy because energy is only for emission)
E is emitted when hf>Φ and ½mv2>0

141
Q

Stopping potential quantum physics Vs

A

eVs= ½mvmax^2

142
Q

Saturation current graph sketching

A 
y axis (current i): ne/t 
Intensity of light proportional to rate of arrival n/t
Intensity= Nhf/tA
I=P/t =(Q/t)(1/A) =(nE/t)(1/A)

X axis (Voltage V): hf=Φ+½mv^2

X axis intersect: KEmax= eVs

143
Q

Deexcitation and excitation of electron

A

Excitation: hf=|Ef-Ei|
absorption spectra, photon is absorbed during upgrade

Deexcitation hf=Ef-Ei
emission spectra, photon is emitted during downgrade

144
Q

Answering the spectra qns for quantum

A
  1. Define spectrum
  2. atom and photon movements, energy levels
  3. emit/absorb
  4. transit energy direction
    1. resultant observation
145
Q

2 components of ouput Xray spectrum

A
  1. characteristic peaks
  2. broad continuous bg

KE loss=Ephoton
qeV=hf=hc/λmin

146
Q

Wavelength for particle (wave-particle duality)
when momentum is given

A

λ =h/p
=h/mv

147
Q

Heisenburg uncertainty principle

A

△p△x > h

MUST BE IN THE SAME DIMENSION

148
Q

Nuclear binding energy

A

E=△mc2
=(total rest mass of reactants-total rest mass of products) c2

149
Q

energy released in a nuclear reaction

A

total binding energy of products–total binding energy of reaction
= (total rest mass of reactants-total rest mass of products) c^2

150
Q

Charges of alpha beta gamma

A

A +2e
B -e
Gamma 0

151
Q

Ioinising power of alpha beta gamma

A

A strong (larger mass, more charge)
B moderate
Gamma weak

152
Q

penetrating power of alpha beta gamma

A

A low
B medium
Gamma high

153
Q

Nuclear eqn of alpha beta gamma

A

A gives out 42H
B gives out 0-1e
Gamma gives out y with unchanged original reactant

154
Q

Activity of radioactive decay/rate

A

A=λN
A= -dN/dt

λ decay constant and A the rate of decay

155
Q

half life t½

A

t½+ ln 2/λ
N=N0(½)n

N/N0= A/A0 = e-λt

A level physics formulas (2 decks)

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