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

2019 VI 07 1430 Seat No.

Time : 2 Hours Electronic Materials & Workshop Practice
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 each question and sub-question
clearly.

(iii) All questions are compulsory.

(iv) Figures to the right indicate full marks.

(v) Draw neat labeled diagrams wherever necessary.

1. (A) Fill in the blanks : 2

(i) The high resistivity conducting material used as contact brush
in electrical machines is ................................ .

(ii) The low resistivity lightweight, silver-colored conducting material
used for manufacturing ACSR conductor is ............................. .

(B) Answer the following in brief : 3+3=6

(i) Draw neat labeled energy band diagrams for Conductors, Semi-
conductors and Insulators.

(ii) State any three applications of each of the following magnetic
materials :

(a) Mild Steel

(b) Silicon Steel.

(C) Answer the following : 2

Write any four applications of Bimetallic Relay.

2. (A) Define the following terms : 2

(i) Magnetostriction

(ii) Thermo-electric Current.

(B) Answer the following : 3+3=6

(i) State any six properties of Mica.

(ii) Draw a neat flowchart for manufacturing process of P.C.B.

(C) Answer the following : 2

State any two applications of each of the following Insulating Materials :

(a) Paper

(b) Porcelain.

3. (A) Fill in the blanks : 2

(i) The instrument used for measuring higher temperature above

357ºC at remote place is ...........................

(ii) The break in path of an electric current in a winding or coil is

known as ............................... circuit fault.

(B) Answer the following : 3

Mention any one application of each of the following tools used in various

workshops :

(a) Long Nose Plier

(b) Cross Cut Screw Driver

(c) Firmer Chisel

(d) Double End Open Jaw Spanner

(e) Claw Hammer

(f) Solid Base Vice.

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

(i) With the help of a neat labeled diagram, explain the Czochralski

Method of growth and purification of Semi-conductor crystal.

Or

(ii) With the help of a neat labeled diagram, explain Zone Refining

or Zone Melting method for growing single semiconductor crystal.

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

(i) Mention any two causes of Short Circuit.

(ii) State any two ways to minimize (reduce) the hysteresis loss in

magnetic materials.

(B) Answer the following in brief : 3

State any three applications of each of the following Semiconductor

Material :

(i) Silicon

(ii) Germanium.

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

(i) Write any ten points on ‘Workplace Safety’ precautions to be taken

in an Assembly Shop.

Or

(ii) Briefly explain the necessity of Overhauling and Servicing of a

motor or an appliance. State any six steps of Overhauling of a

Motor or an appliance.

5. Answer the following : 5×2=10

(i) Define the term ‘Lubrication’. Name any two methods of lubrication

used in electrical domestic appliances.

(ii) State any four advantages of P.C.B.

(iii) What is ‘Mass Soldering’ ? Name any two types of Mass soldering

techniques.

(iv) State any two applications of each of the following Conducting

Materials :

(a) Selenium

(b) Nichrome.

(v) Draw a neat labeled diagram of a General Purpose Relay.