ELECTRICITY AND ELECTRONICS (866)

The syllabus is not intended to be used as a teaching An experimental approach to the subject is envisaged
syllabus, or to suggest teaching order. It is expected and it is assumed that candidates will spend adequate
that teachers will wish to develop the subject in their time on individual experimental work. Questions may
own way. be set requiring descriptions of experimental
procedures. Candidates should also know how to
In the examination, questions will be aimed more at exhibit the results of experiments graphically and how
testing the candidates' understanding of fundamental to make deductions from graphs, e.g. from intercepts
principles, and the application of these principles to and gradient in the case of straight-line graphs,
problem situations, than to their ability to remember a deductions by interpolation.
large number of facts. Some questions will include Candidates will be expected to be conversant with SI
simple calculations. units.
 CLASS XII

There will be two papers in the subject: single phase induction motor types. Uses of AC
motors.
Paper I - Theory: 3 hours…… 80 Marks
4. Wires, cables and electrical wiring. Construction
Paper II - Project Work ……. 20 Marks of various types in domestic and industrial use.
PAPER I (THEORY): 80 MARKS (Solid and stranded cables – how insulated and
protected. Flexes). Selection of cable sizes,
1. Distribution of electric power. Idea of a simple voltage drop and simple calculation on current-
distribution system. Mention of the local power carrying capacity. (Linking of size of cables and
system should be made. flexes with maximum current flow particularly in
relation to the circuits below. Regulation B 23
Overhead and underground cables: advantages (voltage drop). Brief description of the wiring
and uses. D.C and A.C distribution systems: D.C systems. Simple circuitry. (Separation of lighting
2 wire system, 3 wire system; AC distribution and power circuits. Layout of lighting circuits.
transformer (3 phase 3 wire system, 3 phase 4 wire Switch in phase line. Dual switching of lamps.
system). Layout of power circuits - ring and spur/ tree
2. The D.C. generator and motor. Use of split-ring systems.) types - limitations). Introduction to rules
commutators; constructional features. Shunt series and regulations, both local and that of I.E.E.
and compound field connections and their (Sequence of equipment). Effects of overloading.
Protection of circuits and individuals by (a) fuses
characteristics. Starting of D.C. motors. Ideas on
and trips, (b) earthing of metal, (c) mechanical
back e.m.f. protection of cables. Regulations for bathrooms.
Single loop D.C. generator (circuit diagram); Commonsense appreciation of dangerous
parts of a practical generator, lap and wave practices (Simple testing).
windings of armature conductors; armature Different types of insulations used in cables;
reactions, commutation and period of Vulcanised Indian Rubber (VIR), Tough Rubber
commutation (T c ), use of interpoles, emf equation Sheathed (TRS), Poly Vinyl Chloride (PVC).
ϕ PN Z
Eg = × (derivation not required); types of 5. Electrical accessories. Structure and uses of
60 A various types of switches, power outlets, lamp
generators; Excitation of poles: Self-excited and holders, ceiling roses and junction boxes.
separately excited; generator construction: shunt, (Familiarity with these is expected - detailed
series & compound types; no-load and load knowledge of structure is not required). Where
characteristics, voltage, current and power and how they are used.
equations, critical resistance; causes of failure to Structure and uses of switches; types: quick break
build up voltage for generators, applications and knife switch, main switch, metal clad switch, air
simple numericals. break switch, tumbler switch, piano-key switch,
Motors: Working principle of a DC motor; voltage finger touch switch; essential qualities of a switch
equation; significance of back emf; D.C motor and its position in circuits and layouts; power
characteristics. Types of D.C motor constructions- outlets – Plug and Sockets; lamp holders types:
shunt, series and compound; necessity of motor bracket holder, batten holder, pendant holder,
angle holder. Ceiling roses; junction boxes.
starter and protective devices; power equation
Where and how they are used.
applications, uses and numericals.
3. The A.C. motor. Ideas on A.C. motors (single
phase only). The rotating field. Methods of
shunting: capacitance start, split phase start.
Single-phase induction motor types.
A.C. motors (single phase only); idea of rotating
magnetic field: split phase start, capacitor start
6. Introduction to electronics. Concept of electron stabilization circuit, simple numericals. Chokes,
flow. Common components employed in bleeder resistors and their functions.
electronic circuits; resistors, capacitors and
inductors; their structure, types and uses. 9. Vacuum triode. Structure of the vacuum triode
valve. The control grid. Triode valve
Concept of electron flow; passive components characteristics. Triode parameters; anode
employed in electronic circuits. Types of
resistance, mutual conductance and amplification
Resistors: wire wound, carbon composition type,
factors; relationship between the above
variable type (potentiometers, rheostat); colour
code. Types of Inductors: air core, iron-core, parameters. Triode as a voltage amplifier. Bias
ferrite core inductors. Types of Capacitors: fixed voltage, cathode resistor and cathode bypass
and variable types. Fixed type: electrolytic capacitor.
capacitor, non-electrolytic (paper capacitors, Structure of the vacuum triode, control grid,
mica capacitor, ceramic capacitors); variable triode value characteristics, grid cut off voltage.
type - ganged capacitors, their structure, types, Plate characteristics, mutual characteristics;
voltage equations and uses. vacuum tube constants (Triode parameters),
7. Diodes. Thermionic diode; semiconductor diode. relationship between them, simple numericals.
Structure of vacuum diode and semiconductor Triode as voltage amplifier: bias voltage, cathode
diode. resistor and cathode bypass capacitor; current in
Thermionic diode: construction, operation vacuum, causes of tube failure. Significance of
characteristics of vacuum diodes; A.C and D.C vacuum in tubes.
plate resistances, space charge, space charge
limiting region. 10. Semiconductor Transistors. The junction
transistor: PNP and NPN types. Introduction to
Semiconductor diodes: bonds in semiconductors, various methods of construction; their
crystal structure of Germanium and Silicon; effect characteristics including handling procedures and
of temperature on semiconductor; concept of hole precautions.
current; intrinsic and extrinsic semiconductors;
doping, n-type, p type semiconductors, energy Self-explanatory.
band diagrams; majority and minority charge
carries; properties of p-n junction diode, forward 11. Transistor amplifier. Introduction to the common-
bias and reverse bias diagrams and graphs; base, common emitter and common collector
volt-ampere characteristics of p-n junction. amplifiers. Comparison of the voltage, current
Definitions of the following: break down voltage, and power gains and input and output resistances
knee voltage, maximum forward current, Peak (elementary approach only). Phase relationship.
inverse voltage (PIV), maximum power rating. Bias stabilization.
8. Power supply for electronic apparatus. Mains Modes of connections: Common-Base (CB),
transformer. The diode; half wave, full wave and Common-Emitter (CE), Common-Collector (CC)
bridge rectifiers, voltage doubler. Filters; RC amplifiers: current amplification factors (∝, β
filters, chokes, bleeder resistance and its and 𝛾𝛾) and their relationship. Simple numericals
functions. on the above.
Mains transformer; semiconductor diodes as half
wave rectifier, full wave rectifier, bridge rectifier. I/P and O/P characteristics, comparison of the
Forward resistance, forward current, reverse voltage, current and power gain, I/P & O/P
current, derivation for: d.c (average current I dc ). resistance (elementary approach only). Phase
Root mean square (rms) current (I rms ), efficiency relationship, bias stabilization, single stage RC
of rectification (η); advantages, disadvantages coupled amplifier circuit, bias circuit, emitter
and uses, ripple factors; simple numericals. bypass capacitor, transistor current equation
∆ I E = ∆I B +∆I C . Phase reversal in CE mode.
Voltage doublers: Types of filters: RC filter, choke
Input (I/P) filter, π-section filter. Input (I/P) and 12. The amplifier. A typical amplifier voltage and
Output (O/P) graphs. Zener diode for voltage power amplification. Matching of the power
stabilisation, importance of series Resistor in the output stage to a speaker.
 Voltage Amplifier (RC Coupled) circuit; Power List of suggested assignments for Project Work:
amplifier circuit, impedance matching of the 1. Electrical accessories (any five), meters and
power (O/P) stage to the speaker; advantages, equipment (any three) used in the laboratory
disadvantages, frequency responses (qualitative), (along with precautions to be observed).
Applications. Differences between transistors and
tubes. Accessories (tools) used in Laboratory: Soldering
gun, soldering stand, solder (lead), nose plier,
13. Apparatus for reproducing and recording sounds.
wire stripper, line tester, tag-board, breadboard,
Range of hearing, recording and reproducing.
general purpose printed circuit board (PCB).
Characteristics of microphones; types of
microphones: carbon, crystal, moving-coil and Meters and equipment: DC milliammeter, AC
ribbon types. The common types of gramophone milliammeter, DC Voltmeter, AC voltmeter,
Digital Multimeter, Variable DC power supply,
pick-ups. The earphone, crystal and magnetic
tapes. The moving-coil loudspeakers; permanent Fixed DC power supply, Audio signal generator,
magnet. Electrostatic speaker. Cathode Ray Oscilloscope (CRO).

Construction, working, advantages and 2. Electrical Cables, their types, uses and
disadvantages of the above. specifications. (Any 5 types, with one use and
important specifications).
14. Common types of electronic measuring
instruments. Valve voltmeters, transistorized 3. Measuring the values of different types of:
voltmeter, signal generator, oscilloscope, use and (i) resistors using colour code
care of the above instruments.
(ii) capacitors using code number .
Simple circuit diagrams of the above instruments
are expected. Writing the procedure to measure the values of
resistances, capacitances and inductances using
Valve voltmeters (VTVM), transistorized multimeter.
voltmeter, signal generator, oscilloscope (CRT);
uses of Oscilloscope to measure: (a) the peak 4. Different types of switches (any five), circuit
value of an ‘ac’ voltage; (b) the frequency of an protecting devices and their specifications.
electrical signal; (c) the time interval (can be used Switches: single-pole, single-throw (SPST),
as a clock). Multimeter used as voltmeter, ohm- single-pole, double-throw (SPDT), double-pole,
meter and ammeter. single-throw (DPST), double-pole, double-throw
(DPDT), Rotary switch, Push Button switch, relay.
PAPER II (PROJECT WORK): 20 Marks Miniature circuit breaker (MCB), fuse, fuse holder
In addition to the syllabus prescribed above, (show samples), switch action (continuity and
candidates are also required to be assessed in Project discontinuity using multimeter) Specifications;
Work. The Project work will be assessed by the subject current and voltage ratings.
teacher and the Visiting Examiner appointed locally and 5. Distribution of electric power (D.C and A.C
approved by CISCE. distribution) using overhead and underground
All candidates will be required to have completed two cables along with their advantages and uses.
projects from any topic/s covered in theory. 6. V-I Characteristics of a semiconductor diode
Mark allocation for each project (10 marks) *: (PN), its types and use of any one type of
Criteria Marks semiconductor diode.
1. Title of the Project and 1 7. V-I Characteristics of a Zener Diode and its use as
Introduction a voltage regulator.
2. Content 3 8. Half wave and Full wave rectifier (either centre-
3. Presentation and originality 2 tapped or bridge type) with/without filter circuit.
4. Conclusion/Comments/Summary 1 9. Electrical accessories (Power outlets, lamp
5. Viva- Voce (Visiting Examiner) 3 holders, ceiling roses and junction boxes) their
TOTAL 10 structure and uses.
10. Simple circuitry of lighting and power circuits 19. Identify a diode, a transistor, a LED, a resistor, an
(domestic use), their layout and limitations, IC (integrated circuit), and a capacitor from a
following IEE regulations. assorted collection of given items and an analog
multimeter.
11. Principle, construction and working of DC motor
with explanation of any one type of DC motor. 20. Prepare a working model on any one of the
following and prepare a brief report highlighting
12. Characteristics of DC generator and DC motor.
the components used, circuit diagram and a step-
13. Types of microphones (any two) giving their by-step procedure:
construction, working and uses with diagrams.
(i) Automatic Traffic Signal System using
14. Types of loudspeakers (any two) giving their suitable combination of logic gates
construction, working and uses with diagrams.
(ii) Basic gates (OR, AND, NOT) using NAND
15. Construction and working principle of power gates
supply including common faults, causes, testing
(iii) FM Radio Receiver
and repair.
(iv) Fire Alarm System
16. Multimeters and their types including functions
of any one type of multimeter. (v) Electronic Lock
17. Transistor Audio Power Amplifiers (any two (vi) Stepper Motor Controller
types), their advantages, disadvantages and uses.
(vii) Water Level Indicator
18. Principle, construction, working and uses of
(viii) Mobile Charger
Cathode Ray Oscilloscope.

NOTE: No question paper for Project work will be

set by CISCE.
 SAMPLE TABLE FOR PROJECT WORK
S. Unique PROJECT 1 PROJECT 2 TOTAL
No. Identification MARKS
Number A B C D E F G H I J
(Unique ID) of
the candidate Teacher Visiting Average Viva-Voce Total Teacher Visiting Average Viva-Voce Total (E + J)
Examiner Marks by Visiting Marks Examiner Marks by Visiting Marks
(A + B ÷ Examiner (C + D) (F + G ÷ Examiner (H + I)
2) 2)
7 Marks 7 Marks 7 Marks 3 Marks 10 7 Marks 7 Marks 7 Marks 3 Marks 10 Marks 20 Marks
Marks
1

10

*For breakup of the 7 Marks to be awarded separately by the Teacher and the Visiting Examiner, please refer to the table giving the criteria for mark
allocation for each project.

NOTE: VIVA-VOCE (3 Marks) for each Project is to be conducted only by the Visiting Examiner and should be based on the Project only.