Goa Board Class 12 Question Paper Mar 2019 Electronic Materials and Workshop Practice

2019 III 05 1000 Seat No.

Time : 2 Hours Electronics Materials & Workshop Parctice
Subject Code

V 3 3 2

Total No. of Questions : 5 (Printed Pages : 4) Maximum Marks : 50

INSTRUCTIONS : (i) Answer each question on a fresh page.

(ii) Write the number of the questions and sub-ques-
tions clearly.

(iii) All questions are compulsory.

(iv) Figures to the right indicate full marks.

(v) Draw neat labelled diagrams wherever necessary.

1. (A) Fill in the blanks : 2

(i) The low resistivity conducting material used for manufacturing
ACSR conductor is ................. .

(ii) The break in path of an electric current in a winding or coil is
known as ......................... circuit fault.

(B) Answer the following : 6

(i) State any three applications of the following conducting

(a) Tungsten

(b) Selenium.

(ii) Draw neat flow chart for manufacturing process of PCB.

(C) Answer the following : 2

What is a thermocouple ? Draw a neat labelled diagram of a
thermocouple.

2. (A) Define the following terms : 2

(i) Thermo e.m.f.

(ii) Thermoelectric current.

(B) Answer the following : 6

(i) Draw neat labelled enegy band diagrams for conductors,
semiconductors and Insulators clearly showing the values of band
gap energies.

(ii) State any one application of each of the following file :

(a) Flat file

(b) Test lamp

(c) Standard screw driver

(d) Single and open jaw spanner

(e) Bench vice

(f) Flat cold chisel.

(C) Answer the following : 2

With the help of a neat labelled diagram briefly explain the dip soldering
technique.

3. (A) Fill in the blanks : 2

(i) The relay used for counting, selection and logic control system
is ........................ .

(ii) The magnetic material which has Curie temperature of 430ºC
and used for manufacturing current transformer is ............... .

(B) Answer the following : 3

State any three applications of the following semiconductor materials :

(i) Germanium

(ii) Silicon

(C) Answer any one of the following in detail : 5

(i) State any ten points of machine safety precautions to be taken
in the Assembly shop.

Or

(ii) Write any five rules and methods of each of the following :

(a) Sequential steps for dismantling of appliances.

(b) Sequential steps for assembling of appliances.

4. (A) Answer the following in brief : 2

(i) Name any two types of winding wires used in winding shop.

(ii) State any two applications of Bimetallic Relay.

(B) Answer the following : 3

Write any three applications of the following insulating materials :

(i) Mica

(ii) Porcelain.

(C) Answer any one the following in detail : 5

(i) With the help of a neat labelled diagram explain the Horizontal
Bridgman method of Semiconductor crystal growth.

Or

(ii) With the help of a neat labelled diargram explain the Czochralski
method of growth and purification of semiconductor crystal.

5. Answer the following : 5×2=10

(i) List any four advantages of printed circuit boards over conventional

wired boards.

(ii) Write any two applications of each of the following magnetic

(a) Mild steel

(b) Silicon steel.

(iii) Name and explain any two types of varnishes.

(iv) What is lubrication ? Name any two methods of lubrication used in

electrical domestic appliances.

(v) State any four properties of Alnico.