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Unformatted text preview: ONESCHOOL.NET Physics Equation List :Form 5
Wave
Oscillation 1
f=
T f = frequency
T = Period (Hz or s1)
(s) DisplacementTime Graph • Amplitude, Period and Frequency can be found from a DisplacementTime Graph Wave v= fλ v = velocity
f = frequency
λ = wavelength DisplacementDistance Graph λ = Wavelength http://www.oneschool.net/ notes.html 1 (ms1)
(Hz or s1)
(m) ONESCHOOL.NET
Interference λ = Wavelength ax
λ=
D a = Distance between the two wave sources
x = Distance between two successive antinode lines or node lines
D = Distance from the wave sources to the plane where x is
measured. Summary Electricity
Sum of charge Q = ne Q = Charge
n = number of charge particles
e = charge of 1 particle Current Q
I=
t http://www.oneschool.net/ notes.html Q = Charge
I = Current
t = time 2 ONESCHOOL.NET
Potential Difference W
V=
Q V = potential difference,
W = energy
Q = charge (V or JC1)
(J)
(C) V = potential difference,
I = Current
R = Resistance (V or JC1)
(A or Cs1)
(Ω) Ohm’s Law and Resistance V = IR
Resistance R=( R = R1 + R2 1
1
1
+
+ ) −1
R1 R2 R3 Current
Series Circuit Parallel Circuit The current flow into a resistor = the current flow
inside the resistor = the current flows out from the
The current flow into a parallel circuit is equal to the
resistor
sum of the current in each branches of the circuit.
IA = IB = IC
I = I1 + I2
Example If the resistance of the 2 resistors is the same, current
will be divided equally to both of the resistor. In a series circuit, the current at any points of the
circuit is the same. http://www.oneschool.net/ notes.html 3 ONESCHOOL.NET
Potential and Potential Difference
Series Circuit Parallel Circuit The sum of the potential difference across individual
resistor in between 2 points in a series circuit is equal
to the potential difference across the two point.
The potential difference across all the resistor in a
parallel circuit is the same. V = V1 + V2
Example V = V1 = V2
Example Potential Difference and Electromotive Force If we assume that there is no internal resistance in the cell, the potential difference across the cell is equal to
the e.m.f. of the cell. http://www.oneschool.net/ notes.html 4 ONESCHOOL.NET
Electromotive Force and Internal Resistance E = I (R + r) E = V + Ir or E = Electromotive Force
r = internal resistance
V = potential difference,
I = Current
R = Resistance (V)
(Ω )
(V or JC1)
(A or Cs1)
(Ω) 2 methods to find the internal resistance and electromotive force
a. Open Circuit – Close Circuit method
Open Circuit
Close Circuit In open circuit ( when the switch is off), the In close circuit ( when the switch is on), the
voltmeter shows the reading of the e.m.f.
voltmeter shows the reading of the potential
difference across the cell.
•
With the presence of internal resistance, the potential difference across the cell is always
less than the e.m.f..
b. Linear Graph method
From the equation,
E = V + Ir
Therefore
V = rI + E
Gradient od the grapf, m
= internal resistance
Y intercept of the graph, c
= electromotive force
Electrical Energy E = QV E = Electrical Energy
Q = charge
V = potential difference http://www.oneschool.net/ notes.html 5 (J)
(C)
(V or JC1) ONESCHOOL.NET
Electrical Power W
P=
t P = IV P=I R
2 V2
P=
R (W or Js1)
(J)
(s)
(A)
(V)
(Ω) P = Power
W = Work done/Energy change
t = Time
I = Current
V = Potential difference
R = Resistance
Efficiency Electrical efficiency = output power
× 100%
input power Electromagnetism
Root mean Square Value Vrms = Vp
2 Vrms = root mean square voltage
Vp = peak voltage I rms = Ip
2 Irms = root mean square current
Ip = peak current http://www.oneschool.net/ notes.html 6 (V)
(V) (A)
(A) ONESCHOOL.NET
Transformer
Input And Output Of A Transformer Vs
N
=s
Vp N p Vp = input (primary) potential difference
Vs = output (secondary) potential difference
Np = number of turns in primary coil
Ns = number of turns in secondary coil (V)
(V) Power In A Transformer
Ideal Transformer V p × I p = Vs × I s Vp = input (primary) potential difference
Vs = output (secondary) potential difference
Ip = input (primary) current
Is = output (secondary) current (V)
(V)
(A)
(A) Nonideal transformer Efficiency = Vs I s
× 100%
Vp I p Power Transmission
2Steps to find the energy/power loss in the cable
a. Find the current in the cable by the equation P=IV
2
b. Find the Power lost in the cable by the equation P=I R. Electronic
Energy change of electron in an electron gun Kinetic energy electrical potential
=
energy
gain 12
mv = eV
2
2eV
v=
m http://www.oneschool.net/ notes.html v = speed of electron
V = potential difference across the electron gun
e = charge of 1 electron
m = mass of 1 electron 7 (ms1)
(V)
(C)
(kg) ONESCHOOL.NET
Cathode Ray Oscilloscope Vertical scale = Ygain control
Horizontal scale = Time base
Period = Time for 1 complete Oscillation
Frequency, f= 1
T Transistor  Potential Divider Potential difference across resistor R1
= R1
×V
R1 + R2 Potential difference across resistor R2
= http://www.oneschool.net/ notes.html R2
×V
R1 + R2 8 ONESCHOOL.NET Radioactivity
A lpha decay
A
A− 4
4
Z X ⎯⎯→ Z − 2Y + 2 He B eta decay Y+ A
A
Z X ⎯⎯→ Z +1
1
0 0
−1 e 1
0
n→1 p + −1 e Gamma emission A
A
Z X ⎯⎯→ Z X +γ A = nucleon number
Z = proton number
Halflife 1
N = ( )n N0
2 N = Amount of radioisotope particles after nth half life.
N0 = Initial amount of radioisotope particles.
n = number of half life Nuclear Energy  Einstein Formula E = mc 2 m = mass change
c = speed of light
E = energy changed http://www.oneschool.net/ notes.html (kg)
(m s1 )
(J) 9 ...
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 Spring '10
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