ONE-SCHOOL.NET Physics Equation List :Form 5

Physics Equation List :Form 5 Wave Oscillation T f 1 = Displacement-Time Graph f = frequency (Hz or s-1) T = Period (s) • Amplitude, Period and Freque...
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Physics Equation List :Form 5 Wave Oscillation

1 f = T

f = frequency T = Period

(Hz or s-1) (s)

Displacement-Time Graph

•

Amplitude, Period and Frequency can be found from a Displacement-Time Graph

Wave

v= fλ

v = velocity f = frequency λ = wavelength

Displacement-Distance Graph

λ = Wavelength

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1

(ms-1) (Hz or s-1) (m)

ONE-SCHOOL.NET Interference

λ = Wavelength

ax λ= D

a = Distance between the two wave sources x = Distance between two successive anti-node 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

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Q = Charge I = Current t = time

2

ONE-SCHOOL.NET Potential Difference

W V= Q

V = potential difference, W = energy Q = charge

(V or JC-1) (J) (C)

V = potential difference, I = Current R = Resistance

(V or JC-1) (A or Cs-1) (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.

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ONE-SCHOOL.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.

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ONE-SCHOOL.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 JC-1) (A or Cs-1) (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

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5

(J) (C) (V or JC-1)

ONE-SCHOOL.NET Electrical Power

W P= t

P = IV

P=I R 2

V2 P= R

(W or Js-1) (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

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(V) (V)

(A) (A)

ONE-SCHOOL.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)

Non-ideal 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

1 2 mv = eV 2 2eV v= m

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v = speed of electron V = potential difference across the electron gun e = charge of 1 electron m = mass of 1 electron

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(ms-1) (V) (C) (kg)

ONE-SCHOOL.NET Cathode Ray Oscilloscope

Vertical scale = Y-gain 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 =

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R2 ×V R1 + R2

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ONE-SCHOOL.NET

Radioactivity Alpha decay A A− 4 4 Z X ⎯⎯→ Z − 2Y + 2 He

Beta decay

Y+

A A Z X ⎯⎯→ Z +1 1 0

0 −1

e

n→11p + −10 e

Gamma emission

A A Z X ⎯⎯→ Z X

+γ

A = nucleon number Z = proton number Half-life

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

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(kg) (m s-1 ) (J)

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