ISC 2026 Electricity and Electronics Question Paper for Class 12

About this paper

This is the ISC Class 12 Electricity and Electronics paper from the 2026 board examination, code 1226-866. It carries 80 marks and lasts three hours, with an extra fifteen minutes for reading only. All thirteen questions are compulsory. Section A is worth 16 marks and has twelve very short subparts. Section B has eight four-mark questions, and Section C has four eight-mark questions. Internal choices are given in two questions in Section B and in one question in Section C. The paper tests capacitor-start motors, a bridge rectifier, microphones, vacuum-tube constants, filters, the Zener diode, the cathode-ray oscilloscope, domestic wiring, transistor connections and d.c. machines. This copy has the questions only.

Exam

ISC Class 12

Subject

Electricity and Electronics

Year

2026

Paper code

1226-866

Maximum marks

80

Time allowed

3 hours + 15 min reading

Questions

13

Pages

7

Answers included

No, questions only

Paper pattern

• Section A

  16 marks

  Question 1 with twelve very short subparts: multiple-choice items, short answers, a matching exercise and true-or-false statements

• Section B

  32 marks

  Questions 2–9, four marks each; internal choice in two questions

• Section C

  32 marks

  Questions 10–13, eight marks each; internal choice in one question

Topics covered

• Cathode ray oscilloscope
• Series and shunt machines
• Capacitor-start induction motor
• Bridge rectifier
• Moving-coil microphone
• Vacuum-tube constants
• Zener diode
• Filters and p-n junction
• Domestic wiring
• Transistor amplifiers
• DC motor starters and back emf
• Armature reaction

Questions from this paper

1. With the help of a labelled circuit diagram, explain how a capacitor is used to self-start a single-phase a.c. motor.
2. Draw a labelled circuit diagram of a bridge rectifier using semiconductor diodes.
3. Explain the working of a moving-coil microphone.
4. Define amplification factor, a.c. plate resistance and mutual conductance for a vacuum tube, and write the relationship among them.
5. State the function of the starter resistor, the no-volt release coil and the overload release coil in a d.c. motor, and explain the significance of back emf.
6. Compare the ripple factor and the efficiency of a full-wave rectifier and a half-wave rectifier.