Physics Formulas
Physics Formulas
Physics Formulas
Magnitude: a = la = /a+ a + a?
Dot product: ab= agby + ayby t azb, = ab cos Conical pendulum: T=2n/Lcos
mg
Cross product:
1.4: Work, Power and Energy
Work: W= F.5= FS cos 8, WN= [Y.da
| x Qj = ab sin Kinetic energy: K = mu =
Potential energy: F=-U/Ôz for conservative forces.
1.2: Kinematics
Ugravitational = mgh, Uspring = ka?
Average and Instantaneous Vel. and Accel.:
Day = AY/At, Dnst dr/dt Work done by conservative forces is path indepen
ainst = di/dt dent and depends only on initial and final points:
aav = At/At Fconservative d= 0.
Work-energy theorem: W = AK
Mechanical energy: E=U+K. Conserved if forces are Rotation about an axis with constant a:
conservative in nature.
w= Wo t at, e= wt +at, w?- w?=2ae
Power Pav AW
A
Pnst = F.
CM of few useful configurations: ring disk shell sphere rod hollow solid rectangle
1. m1, m2 separated by r:
mË +m2
Theorem of Parallel Axes: I, = len + md?
CII
6. Solid Hemisphere: ye =
Conservation of L: Text =0 ’ L= const.
7. Cone: the height of CM from the base is h/4 for Equilibrium condition: SF =6, Si=0
the solid cone and h/3 for the holow cone.
Kinetic Energy: Krot =lu?
Motion of the CM: M =)m; Dynamics:
First: Elliptical orbit with sun at one of the focus. Modulus of rigidity: Y = B= -VA, =8
Second: Areal velocity is constant. (. dLjdt = 0).
An
Third: T² x a'. In circular orbit T?= GM Compressibility: K
==-+
lateral strain AD/D
Poisson's ratio: o = pngitudinal strainAIJI
1.8: Simple Harmonic Motion Elastic energy: U=; stress x strain X volume
Hooke's law: F=-kz (for small elongation z.)
Acceleration: a = = m
2=-w Surface tension: S= F/l
Time period: T = 2 = 2r Surface energy: U = SA
Displacement: z = Asin{wt + ) Excess pressure in bubble:
Springs in series:
A/2
Progressive wave travelling with speed v:
1. Boundary conditions: y =0 at æ
y=f(t -a/v), ’ t2; y=f(t + æ/v), -*
2. Allowed Freq.: L =(2n +1), v=n /
V , n=
0.1,2,. ...
Standing Waves:
Standing longitudinal waves:
A/4
P1 = Po sin w(t - */v), p2 = Po sin w(t + æ/v)
V1 = A1 sin(kæ wt), y2 = Ag sin(kæ + wt) p=P1 t p2 = 2po cos kæ sin wt
y=y1 t y2 = (2A cos kæ) sin wt
m= (7+)$ nodes; n=0, 1,2,...
n-, antinodes. n = 0, 1, 2,...
Closed organ pipe:
Phase difference: 8 = Az
Interference Conditions: for integer n,
Open organ pipe:
2rT, constructive;
O (2n +1)m, destructive,
1. Boundary condition: y =0at a =0 constructive;
Allowed freq.: L = n, v= n n=l, 2,... Aæ =
(n+) A, destructive
2. Fundamental/1*t harmonics: V =
3. 1t overtone/2nd harnonics: V= 2uo = E Intensity:
4. 2nd overtone/3rd harmonics: y = 3u0 = I=h+h+ 2/Ihlh cos 8,
5. All harmonics are present. Imta (Vh- VE)
h=h:l= 4lo cos",Imax =4lo, Imin = 0
Fringe width: w=
Resonance column: Optical path: Ar'= uAr
d
(i) the image and the object are equidistant from mir
ror (ii) virtual image of real object
f2
Spherical Mirror:
3.3: Optical Instruments
Simple microscope: m= D/f in normal adjustment.
1. Focal length f = R/2 Objective Eyepiece
2. Mirror equation: +=
3. Magnification: m= Compound microscope:
3.4: Dispersion
Deviation by a prism:
Cauchy's equation: =0 + A> 0
Dispersion by prism with small A and i:
8=i+i- A, general result 1. Mean deviation: y, = (y -1)A
=
sin i=i for minimum deviation 2. Angular dispersion: = (y -r)A
sin
Dispersive power: w = B (if Aand i small)
On =(u- 1)A, for small A
Dispersion without deviation:
m=
4 Heat and Thermodynamics 4.4: Theromodynamic Processes
Pressure: p= pums
COP = =
Equipartition of energy: K = }kT for each degree of
freedom. Thus, K = Tfor molecule having f de Entropy: AS =, Sf - S = f
grees of freedoms.
Const. T: AS = , Varying T : AS = ms ln
Internal energy of n moles of an ideal gas is U = nRT.
Adiabatic process: AQ =0, pV = constant
4.3: Specific Heat
4.5: Heat Transfer
Specific heat: s= máT
Conduction: 4 =-KAAT
Latent heat: L = Q/m
Thermal resistance: R= KA
Specific heat at constant volumne: Cy = AT..
Raetes = Ry +Ry =+(+)
Specific heat at constant pressure: Cp =
K2 A2
Relation between G and Cy: Cp - Cy =R Hparallel =t=(K1A1 + K2A2)
Field of a uniformly charged ring on its axis: Resistance of a wire: R= l/A, where p =1l/o
Temp. dependence of resistance: R= Ro(1 + aAT)
Ohm's law: V = iR
E and V of a uniformly charged sphere:
1_Qr for r <R Kirchhoff's Laws: () The Junction Lau: The algebraic
E= sum of all the currents directed towards a node is zero
for r > R
R i.e., Enode I; = 0. (ii) The Loop Law: The algebraic
V=spg3- e). tor r<R
for r > R
V
sum of all the potential differences along a closed loop
in a circuit is zero i.e., loopA Vi = 0.
4TEn r
R
for r < R R1 R2
V= 1_4 for r > R
R Wheatstone bridge: R
R
Field of aline charge: E= r
Balanced if R/Ry = Rs/Ra.
Field of an infinite sheet: E=
Electric Power: P= V/R= I'R= IV
Field in the vicinity of conducting surface: E =
Energy of a magnetic dipole placed in B:
Galvanometer as an Ammeter: U= -iB
i-i,
iG= (i- i,)s B
Hall effect: V,. = Bi
ned
Galvanometer as a Voltmeter:
at) = Cv1-e te
Field due to a straight conductor:
Discharging of capacitors: g(t) = goe c g(t)
Seeback effect: T
To T
Field on the axis of a ring:
1, Thermo-emf: e= aT +}6T?
2. Thermnoelectric power: de/dt = a + bT.
3. Neutral temp.: T, = -a/b.
4. Inversion temp.: T;=-2a/b.
Thomson effect: emf e= = cThomson
aed heat
= oAT.
Faraday's law of electrolysis: The mass deposited is
ia?
Bp = 2(a2+d²y3/2
Horizontal . . B
Force on a current carrying wire: Angle of dip: B, = B cos & N
B.
Magnetic moment of a current loop (dipole): Moving coil galvanometer: niAB = k9, i=¤
à =iÃ
Time period of magnetometer: T= r/ B,
Torque on a magnetic dipole placed in B: 7= ixB Permeability: B
= ui
5.7: Electromagnetic Induction
RC circuit:
Magnetic flux: =fB- da eo sinwt
R
eo sin wt
Z= R+wL', tan =
Motional emf: e = Blu
Decay of current in LR circuit: i= ige L7R Speed of the EM waves in vacuum: c=l/uo¬o
to
0.37io
Alternating current:
Imepedance: Z = eo/io
6 Modern Physics
6.1: Photo-electric effect
Population at time t: N = NÍe-At NG
ti/2
Photon's energy: E = hu = hc/A
Photon's momentum: p = h/) = E/c Half life: t/2 = 0.693/A
Max. KE of ejected photo-electron: Kmax = hu Average life: tay =1/)
Threshold freq. in photo-electric effect: v = /h Population after n half lives: N = No/2".
V Mass defect: Am = (Zm, + (A- Z)m] - M
Stopping potential: V, =e () Binding energy: B= |Zm, + (A - Z)m, - M]e
Q-value: Q= U;-U,
de Broglie wavelength: A= h/p Energy released in nuclear reaction: AE Amc?
where Am == mreactants mproducts
mZe 13.6Z2
eV
En = Seoh2n2 En = Half Wave Rectifier:
R$Output
Radius of the nth Bohr's orbit:
eoh²n2 n²ao Full Wave Rectifier:
ao = 0.529 A
TmZe
Amplification by atriode: =- AV
Relation between rps L, and gm: = Ip X Jm
Ka
1
1
1 0
1
Decay rate: dt
=-AN