ISC Class 12 Syllabus 2027 Electricity and Electronics

ISC YEAR 2027

INDIAN SCHOOL CERTIFICATE
EXAMINATION

ELECTRICITY
&
ELECTRONICS
(866)

February 2025
____________________________________________________________________________________________

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MISSION STATEMENT

The Council for the Indian School Certificate
Examinations is committed to serving the nation's
children, through high quality educational
endeavours, empowering them to contribute towards
a humane, just and pluralistic society, promoting
introspective living, by creating exciting learning
opportunities, with a commitment to excellence.

ETHOS OF CISCE

Trust and fair play.
Minimum monitoring.
Allowing schools to evolve their own niche.
Catering to the needs of the children.
Giving freedom to experiment with new ideas
and practices.
Diversity and plurality - the basic strength for
evolution of ideas.
Schools to motivate pupils towards the
cultivation of:
Excellence - The Indian and Global
experience.
Values - Spiritual and cultural - to be the bedrock
of the educational experience.
Schools to have an 'Indian Ethos', strong roots in
the national psyche and be sensitive to national
aspirations.

CLASS XII

There will be two papers in the subject: 3. The A.C. motor. Ideas on A.C. motors (single
phase only). The rotating field. Methods of
Paper I - Theory: 3 hours…… 80 Marks
shunting: capacitance start, split phase start.
Paper II - Project Work ……. 20 Marks Single-phase induction motor types.
A.C. motors (single phase only); idea of rotating
magnetic field: split phase start, capacitor start
PAPER I (THEORY): 80 Marks single phase induction motor types. Uses of AC
motors.
1. Distribution of electric power. Idea of a simple
distribution system. Mention of the local power 4. Wires, cables and electrical wiring. Construction
of various types in domestic and industrial use.
system should be made.
(Solid and stranded cables – how insulated and
Overhead and underground cables: advantages protected. Flexes). Selection of cable sizes,
and uses. D.C and A.C distribution systems: D.C voltage drop and simple calculation on current-
2 wire system, 3 wire system; AC distribution carrying capacity. (Linking of size of cables and
transformer (3 phase 3 wire system, 3 phase 4 wire flexes with maximum current flow particularly in
system). relation to the circuits below. Regulation B 23
(voltage drop). Brief description of the wiring
2. The D.C. generator and motor. Use of split-ring systems. Simple circuitry. (Separation of lighting
commutators; constructional features. Shunt series and power circuits. Layout of lighting circuits.
and compound field connections and their Switch in phase line. Dual switching of lamps.
characteristics. Starting of D.C. motors. Ideas on Layout of power circuits - ring and spur/ tree
back e.m.f. systems.) types - limitations). Introduction to rules
and regulations, both local and that of I.E.E.
Single loop D.C. generator (circuit diagram); (Sequence of equipment). Effects of overloading.
parts of a practical generator, lap and wave Protection of circuits and individuals by (a) fuses
windings of armature conductors; armature and trips, (b) earthing of metal, (c) mechanical
reactions, commutation and period of protection of cables. Regulations for bathrooms.
commutation (T c ), use of interpoles, emf equation Commonsense appreciation of dangerous
ϕ PN Z practices (Simple testing).
Eg= × (derivation not required); types of
60 A Different types of insulations used in cables;
generators; Excitation of poles: Self-excited and Vulcanised Indian Rubber (VIR), Tough Rubber
separately excited; generator construction: shunt, Sheathed (TRS), Poly Vinyl Chloride (PVC).
series & compound types; no-load and load
5. Electrical accessories. Structure and uses of
characteristics, voltage, current and power
various types of switches, power outlets, lamp
equations, critical resistance; causes of failure to
holders, ceiling roses and junction boxes.
build up voltage for generators, applications and (Familiarity with these is expected - detailed
simple numericals. knowledge of structure is not required). Where
Motors: Working principle of a DC motor; voltage and how they are used.
equation; significance of back emf; D.C motor Structure and uses of switches; types: quick break
characteristics. Types of D.C motor constructions- knife switch, main switch, metal clad switch, air
shunt, series and compound; necessity of motor break switch, tumbler switch, piano-key switch,
starter and protective devices; power equation finger touch switch; essential qualities of a switch
applications, uses and numericals. and its position in circuits and layouts; power
outlets – Plug and Sockets; lamp holders types:
bracket holder, batten holder, pendant holder,

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angle holder. Ceiling roses; junction boxes. Output (O/P) graphs. Zener diode for voltage
Where and how they are used. stabilisation, importance of series Resistor in the
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 9. Vacuum triode. Structure of the vacuum triode
inductors; their structure, types and uses.
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 parameters. Triode as a voltage amplifier. Bias
code. Types of Inductors: air core, iron-core, voltage, cathode resistor and cathode bypass
ferrite core inductors. Types of Capacitors: fixed
capacitor.
and variable types. Fixed type: electrolytic
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 10. Semiconductor Transistors. The junction
limiting region. 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 11. Transistor amplifier. Introduction to the common-
carries; properties of p-n junction diode, forward base, common emitter and common collector
bias and reverse bias diagrams and graphs; amplifiers. Comparison of the voltage, current
volt-ampere characteristics of p-n junction.
and power gains and input and output resistances
Definitions of the following: break down voltage,
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 I/P and O/P characteristics, comparison of the
wave rectifier, full wave rectifier, bridge rectifier. voltage, current and power gain, I/P & O/P
Forward resistance, forward current, reverse
resistance (elementary approach only). Phase
current, derivation for: d.c (average current I dc ).
relationship, bias stabilization, single stage RC
Root mean square (rms) current (I rms ), efficiency
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

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12. The amplifier. A typical amplifier voltage and 3. Presentation and originality 2
power amplification. Matching of the power 4. Conclusion/Comments/Summary 1
output stage to a speaker. 5. Viva- Voce (Visiting Examiner) 3
Voltage Amplifier (RC Coupled) circuit; Power TOTAL 10
amplifier circuit, impedance matching of the
power (O/P) stage to the speaker; advantages, List of suggested assignments for Project Work:
disadvantages, frequency responses (qualitative), 1. Electrical accessories (any five), meters and
Applications. Differences between transistors and equipment (any three) used in the laboratory
tubes. (along with precautions to be observed).
13. Apparatus for reproducing and recording sounds. Accessories (tools) used in Laboratory: Soldering
Range of hearing, recording and reproducing. gun, soldering stand, solder (lead), nose plier,
Characteristics of microphones; types of wire stripper, line tester, tag-board, breadboard,
microphones: carbon, crystal, moving-coil and general purpose printed circuit board (PCB).
ribbon types. The common types of gramophone Meters and equipment: DC milliammeter, AC
pick-ups. The earphone, crystal and magnetic milliammeter, DC Voltmeter, AC voltmeter,
tapes. The moving-coil loudspeakers; permanent Digital Multimeter, Variable DC power supply,
magnet. Electrostatic speaker. Fixed DC power supply, Audio signal generator,
Construction, working, advantages and Cathode Ray Oscilloscope (CRO).
disadvantages of the above. 2. Electrical Cables, their types, uses and
14. Common types of electronic measuring specifications. (Any 5 types, with one use and
instruments. Valve voltmeters, transistorized important specifications).
voltmeter, signal generator, oscilloscope, use and
3. Measuring the values of different types of:
care of the above instruments.
Simple circuit diagrams of the above instruments (i) resistors using colour code
are expected. (ii) capacitors using code number .
Valve voltmeters (VTVM), transistorized Writing the procedure to measure the values of
voltmeter, signal generator, oscilloscope (CRT); resistances, capacitances and inductances using
uses of Oscilloscope to measure: (a) the peak multimeter.
value of an ‘ac’ voltage; (b) the frequency of an 4. Different types of switches (any five), circuit
electrical signal; (c) the time interval (can be used protecting devices and their specifications.
as a clock). Multimeter used as voltmeter, ohm-
meter and ammeter. Switches: single-pole, single-throw (SPST),
single-pole, double-throw (SPDT), double-pole,
PAPER II (PROJECT WORK): 20 Marks single-throw (DPST), double-pole, double-throw
(DPDT), Rotary switch, Push Button switch, relay.
In addition to the syllabus prescribed above, Miniature circuit breaker (MCB), fuse, fuse holder
candidates are also required to be assessed in Project (show samples), switch action (continuity and
Work. The Project work will be assessed by the subject discontinuity using multimeter) Specifications;
teacher and the Visiting Examiner appointed locally and current and voltage ratings.
approved by CISCE.
5. Distribution of electric power (D.C and A.C
All candidates will be required to have completed two distribution) using overhead and underground
projects from any topic/s covered in theory. cables along with their advantages and uses.
Mark allocation for each project (10 marks) *: 6. V-I Characteristics of a semiconductor diode
Criteria Marks (PN), its types and use of any one type of
1. Title of the Project and 1 semiconductor diode.
Introduction 7. V-I Characteristics of a Zener Diode and its use as
2. Content 3 a voltage regulator.

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8. Half wave and Full wave rectifier (either centre- 19. Identify a diode, a transistor, a LED, a resistor, an
tapped or bridge type) with/without filter circuit. IC (integrated circuit), and a capacitor from a
assorted collection of given items and an analog
9. Electrical accessories (Power outlets, lamp
multimeter.
holders, ceiling roses and junction boxes) their
structure and uses. 20. Prepare a working model on any one of the
following and prepare a brief report highlighting
10. Simple circuitry of lighting and power circuits
the components used, circuit diagram and a step-
(domestic use), their layout and limitations,
by-step procedure:
following IEE regulations.
(i) Automatic Traffic Signal System using
11. Principle, construction and working of DC motor
suitable combination of logic gates
with explanation of any one type of DC motor.
(ii) Basic gates (OR, AND, NOT) using NAND
12. Characteristics of DC generator and DC motor.
gates
13. Types of microphones (any two) giving their
(iii) FM Radio Receiver
construction, working and uses with diagrams.
(iv) Fire Alarm System
14. Types of loudspeakers (any two) giving their
construction, working and uses with diagrams. (v) Electronic Lock
15. Construction and working principle of power (vi) Stepper Motor Controller
supply including common faults, causes, testing
(vii) Water Level Indicator
and repair.
(viii) Mobile Charger
16. Multimeters and their types including functions
of any one type of multimeter.
17. Transistor Audio Power Amplifiers (any two NOTE: No question paper for Project work will be
types), their advantages, disadvantages and uses. set by CISCE.
18. Principle, construction, working and uses of
Cathode Ray Oscilloscope.

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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

2

3

4

5

6

7

8

9

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.

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