Welcome great EduPodian, here is your Second Term SS3 Physics Lesson Note excerpt.
Scheme of Work
1 Alternating Current (I)
2 Alternating Current (II)
3 Models of the Atom
4 Radioactivity (I)
5 Radioactivity (2)
6 Energy Quantization
7 Photo-Electricity (x-ray)
8 Conduction of Electricity in gases.
9 Wave- Particle Paradox
10 Rockets and Satellites; Component parts and functions Basic Electronics;
Semiconductors.
REFERENCE TEXTBOOKS AND PAST QUESTIONS
• New School Physics by Prof. M.W Anyakoha.
• New System Physics by Dr. Chow.et.al
• WAEC past Questions pack
• UTME past Question pack
• MASTERS Physics Practical Manual.
Week 1:
TOPIC: ALTERNATING CURRENT(I)
CONTENT
Alternating Current Circuit
Graphical Representation
Peak and R.M.S. Values
A.C circuits are circuits through which an alternating current flows. Such circuits are used extensively in power transmission, radio and television, computer technology, telecommunication and in medicine. It varies sinusoid ally or periodically, in such a way as to reverse its direction periodically. The commonest form of such a.c can be represented by;
I = Io sin 2π ft……………………………………………………………………… 1
= Io sin wt
I is the instantaneous current at a time t, Io is the maximum ( or peak ) value of current or its amplitude; f is the frequency and w = ( 2π ft) us the angular velocity, (wt) is the phase angle of the current
Also,
V = Vo sin 2 π ft…………………………………………………………………………………..2
= Vo sin wt
Examples
If an a.c voltage is represented by 1f
V = 4 sin 900 πt, calculate the peak and instantaneous voltage
The peak voltage, Vo = 4v
2πft = 900πt
f = 900
2
f = 450Hz
w = 2πf = 900π
Peak, and r.m.s. values of a.c
EVALUATION
1. Differentiate between peak and r.m.s voltage.
2. Calculate the peak and instantaneous voltage of an a.c source represented by; V = 5 sin 500∏t.
Variation of alternating current (or voltage) with time
An alternating current ( or voltage) varies sinusoidally as shown in the diagram above. It is a sine waveform. The amplitude or peak value of the current Io is… Click here to order the complete Physics Lesson Note for SS3 second term
Week 2:
TOPIC: ALTERNATING CURRENT (II)
CONTENT
- C in Resistor, inductor and capacitor
- Energy in inductance, Reactance and impedance
- Vector Diagram
- Power in A/C
- Resonance and its applications
At any instant, the current through the resistor R, is I an the voltage across it is V
From ohm’s law, V = IR
Thus the current is given by I = V
R.
But V = Vo sin wt
I = V = Vo sin wt
R R
I = Io sin wt
The voltmeter and ammeter connected in the circuit will read the r.m.s values of voltage and current
I r.m.s. = Vr.m.s
- …………………………………………………………………..4
The voltage and the current are said to be in phase or in step with each other . This means that both of them attain their maximum, zero and minimum values at the same instant in time.
Capacitance in an a.c circuit
In the circuit… Click here to order the complete Lesson Note on Physics SS3 second term
Week 3:
MODELS OF ATOMS
CONTENT
Thompson, Rutherford, Bohr Models and Limitations
Assumption of Bohr theory
Electron Cloud Model
Structure of Nucleus, Protons, Isotopes
THOMPSON MODEL
Thompson proposed an atomic model which visualized the atom as a homogenous sphere of positive charge inside of which are embedded negatively charged electrons.
He also determined the ratio of the charged to mass, e/m , of electrons, and found e/m to be identical for all cathode rays particles, irrespective of the kind of gas in the tube or the metal the electrons are made of… Click here to order the complete second term Physics Lesson Note for SS3
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