ELEKTRIESE TEGNOLOGIE

Transcription

1 NATIONAL SENIOR CERTIFICATE GRAAD 10 ELEKTRIESE TEGNOLOGIE MEI JUNIE 2015 PUNTE: 150 TYD: 2 ure Hierdie vraestel bestaan uit 7 bladsye.

2 2 INSTRUKSIES: 1. Hierdie vraestel bestaan uit VYF vrae. 2. Beantwoord AL die vrae. 3. Sketse en diagramme moet groot, netjies en ten volle benoem wees. 4. Alle berekeninge moet getoon en korrek tot twee desimale plekke afgerond wees. 5. Nommer die antwoorde korrek volgens die nommeringstelsel wat in hierdie vraestel gebruik is. 6. Nie-programmeerbare sakrekenaars mag gebruik word. 7. Wys die eenhede vir al die antwoorde van die berekeninge. 8. n Formuleblad word verskaf aan die einde van hierdie vraestel. 9. Skryf netjies en leesbaar..

3 3 VRAAG 1: BEROEPS GESONDHEID EN VEILIGHEID. 1.1 Noem die primêre nood telefoon nommer in Suid Afrika. (1) 1.2 Verduidelik die term goeie huishouding in die elektriese tegnologie omgewing. (2) 1.3 Onveilige toestande is die oorsaak van vele ongelukke. Noem TWEE onveilige toestande in die elektriese werkswinkel. (2) 1.4 Noem VYF stappe wat jy onmiddelik sal neem wanneer iemand n elektriese skok opgedoen het. (5) 1.5 Identifiseer die kleur van die volgende veilighed tekens in 'n elektriese werkswinkel. (5) (1) (1) (1) (1) (1) [15]

4 4 VRAAG 2: GEREEDSKAP EN MEETINSTRUMENTE 2.1 Verwys na die diagram in FIGUUR 2.1 en antwoord die volgende vrae: FIGUUR 2.1 SKROEWEDRAAIERS Daar is twee tiepes skroefkoppe waarvan ons gebruikmaak in die elektriese tegnologie werkswinkel. Noem die TWEE tiepes skroewedraaiers om die skroewe los en vas te draai (2) Noem TWEE maniere waarop skroewedraaiers in goeie werkende toestand ver baie jare gehou kan word (2). 2.2 Noem die rede hoekom die skag van n elektrisiën se skroewedraaier met plastiek of rubber bedek moet word. (2) 2.3 Noem DRIE voordele van n digitale multimeter soos in vergelyking met analoog multimeters. 2.4 Noem DRIE toetse wat met n isolasieweerstand toetser gedoen kan word.(megger). 2.5 Verduidelik waarom dit belangrik is om te soldeer/desolder in 'n goed geventileerde vertrek. (2) [15] VRAAG 3: BASIESE BEGINSELS VAN ELEKTRISITEIT & ELEKTRIESE STROOMBANE. 3.1 Verduidelik die verskil tussen elektronstroomvloei en konvensionelestroomvloei. (4) 3.2 Definieer die terme vry elektrone. 3.3 Skryf Ohm se wet in woorde. 3.4 Noem VIER faktore wat die weerstand van n geleier beïnvloed. (4) 3.5 Maak n netjiese en vol benoemde skets van n silikon atoom deur van die Bohr model gebruik te maak. (4)

5 5 3.6 Bestudeur die kring in FIGUUR 3.1. R1 R3 R2 FIGUUR 3.1: KOMBINASIEBAAN R1 = 10 Ω R2 = 20 Ω R3 = 30 Ω Bereken die volgende: 12 V Die totale weerstand van die stroombaan. (6) Die totale stroom wat van die toevoer getrek word Die spanningsval oor R Die spanningsval oor R Die stroomvloei deur R Gee die waarde van die toevoerspanning na privaat wonings in Suid Afrika. (1) 3.8 Gee die waarde van die frekwensie waarteen die toevoerspanning opgewek word in Suid Afrika. (1) 3.9 Maak n netjiese benoemde skets van die intermediêre stroombaan om een lig te beheer. Dui ook die posisie van die miniatuur stroombreker aan. (7) 3.10 Toon met behulp van 'n kringdiagram hoe 'n geiser sal gekoppel word aan die hoof toevoer. (6) 3.11 Noem die miniatuur stroombreker ( MCB ) graderings wat gebruik word vir die volgende installasies: Hooftoevoer. (1) Geiser (1)

6 Stoof. (1) Beligtingsstroombaan. (1) 3.12 Noem die verskil tussen die DRIE HITTE en VYF HITTE stoof skakelaar. (2) 3.13 Gloeilampe moet altyd in parallel verbind word. Verduidelik hoekom dit so moet wees. [60] VRAAG 4: TOEVOER. 4.1 Noem enige VIER toevoer bronne. (4) 4.2 Definieer die volgende: Potentiaal verskil (PV). (2) Elektromotoriesekrag. (EMK) (2) 4.3 Noem die verskiul tussen die primêre selle en die sekondêre selle. (2) 4.4 Teken die IEC simbool van n sonkrag sel. en gee DRIE toepassings van die paneel. (2) 4.5 Noem DRIE toepassings van die sonkragsel. 4.6 Bereken die terminaal spanning van n sel met n EMK van 1,5 V en n interne weerstand van 0,4 Ω. Die sel lewer n stroom van 0,2 A. 4.7 n Battery bestaan uit VYF selle in serie,elke sel het n EMK van 1.5 V en n interne- weerstand van 0.5 Ω. Bereken: Die totale EMK van die battery Die totale interne weerstand van die battery. 4.8 Maak n netjiese benoemde skets van n blokdiagram van n kragbron. (6) [30] VRAAG 5: ELEKTRONIESE KOMPONENTE. 5.1 Defineer die terme kapastansie. (2) 5.2 Noem VIER tiepes kapasitors. (4) 5.3 TWEE kapasitors van 20 μf en 40 μf onderskeidelik word in serie verbind oor n 100 V gelykstroom toevoer.

7 7 Bereken: Die totale kapastansie Die totale lading Die lading op elke kapasitor. (2) 5.4 Maak netjiese benoemde IEC simbole van die volgende komponente: Reostaat. (2) Zener diode (2) LUD (2) 5.5 Voltooi die onderstaande tabel. Dit is nie nodig om die tabel in jou antwoord boek oor te teken nie. Skryf net die antwoord langs die regte vraag nommer. (6) Vrae Kleurkode Weerstand waarde Ω Bruin, Bruin, Rooi Ω 5.6 Verduidelik die werking van n diode met verwysing na die vorentoe voorspanning (4) [30] TOTAAL 150

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9 May/June 2015 NATIONAL SENIOR CERTIFICATE GRADE 10 ELECTRICAL TECHNOLOGY MEMORANDUM MAY/JUNE 2015 MARKS: 150 TIME: 2 hours Please turn over

10 [Type text] [Type text] May/June 2015 INSTRUCTIONS AND INFORMATION This question paper consists of FOUR questions. Answer ALL the questions. Sketches and diagrams must be large, neat and fully labelled. Show ALL calculations and round off correctly to TWO decimal places. Number the answers correctly according to the numbering system used in this question paper. You may use a non-programmable calculator. Show the units for all answers of calculations. A formula sheet is provided at the end of this question paper. Write neatly and legibly.

11 QUESTION 1: OCCUPATIONAL HEALTH AND SAFETY (1) 1.2 A place for everything and everything in its place (2) Inadequate guarding Poor ventilation Slippery floor Overcrowding in a workshop Insufficient light in a workshop (any two) Look first; don t touch the victim Turn off the main power supply Remove the person from the live wire with an isolated object Do not move the victim unless the person is at immediate danger Determine if the victim has any external injuries like burn mark etc. Cover the victim with a blanket to maintain body heat. Call for medical help. (2) (5) White on a green background (1) Black boarder with a yellow centre and black symbol inside (1) Red background with white symbol inside (1) Red on white background (1) White on blue background (1) [15] QUESTION 2: MEASURING INSTRUMENTS AND HAND TOOLS To turn screws in or out of pieces of material (1) Flat screw driver Philips or Star screw driver (2) Always use the correct screwdriver for the correct job Make sure the tip of the screwdriver fits properly into the screw slot Do not use it as a lever or chisel (2) 2.2 To prevent electric shock (2) 2.3 Are very accurate Are not influenced by external magnetic field

12 Have a quick respond time Easy to read Very robust and can withstand reasonable levels of shock, vibration and temperature change. (any three) 2.4 For open circuit For short circuit Earth continuity Insulation resistance between conductors Insulation resistance between conductors and earth The polarity of switches. (any three) 2.5 When you solder or desolder, harmful fumes are generated. It is therefore important to work in a well- ventilated room to prevent you from inhaling harmful fumes. (2) QUESTION 3: BASIC PRINCIPLE OF ELECTRICITY & ELECTRIC CIRCUITS [15] 3.1 Conventional current flow The flow of current from positive to negative Electron flow The flow of the electrons from negative to positive (4) 3.2 An electron in the outer energy level is so weakly attracted that it can move freely between the other electrons when displaced from its orbit. 3.3 The current flowing through the circuit is proportional to the applied voltage and inversely proportional to the resistance of the circuit. 3.4 The material of which is made (specific resistance) Its cross sectional area Its length Its temperature at a given time (4) 3.5 Electroncs Nucleus Orbits/shells. One mark for the correct drawing of the silicon atom (4)

13 R1 XR2 Rp = R1 R 2 10X 20 = =6.67Ω R T = R p + R 3 = = Ω I T = V/R T = 12/36.67 = 0.33 A V R3 = IR 3 = 0.33 x30 = 9.9 V (6) V P = V R1 V R1 = IR P = 0.33 x 6.67 = 2.2 V I R1 = V R1 /R 1 = 2.2/10 = 0.22 A V (1) Hz (1)

14 3.9 Circuit breaker L Two-way switch N Intermediate switch Lamp (7) 3.10 Circuit breaker N L Double pole isolator Geyser Thermostat Element E (7) A (1) A (1) A /40 A (1) A (1) 3.12 A three- heat stove switch has 4 switch positions, while a five- heat stove switch have 6 positions. (2) 3.13 We connect lights in parallel so that if one of the bulbs is not working, the others can continue to work. (2) [60] QUESTION 4: POWER SUPPLIES 4.1 Coal energy Natural energy

15 Petroleum Wind power Solar energy Nuclear energy Hydropower Geothermal.(any four) (4) Pd - Is the voltage measured across the battery terminals when current is flowing. (2) EMF-Is the voltage measured across the battery terminals when there is no current is flowing. (2) 4.3 Primary cells cannot be recharged, while secondary cells can be recharged. (2) _ (2) 4.5 Uses: To power traffic lights For geysers in domestic installation Provide power for telecommunication equipment 4.6 V = E (I x r) = 1.5 (0.4 x 0.2 ) = 1.42 A E T = e 1 + e 2 + e 3 + e 4 + e 5 = = 9 V r T = r 1 + r 2 + r 3 + r 4 + r 5

16 = = 2.5 Ω V ac supply Transformer Rectifier Smoothing Regulator Regulated output (6) [30] QUESTION 5: ELECTRONIC COMPONENTS 5.1 Capacitance is the storage of a charge when plates are connected to voltage. Capacitance is the ability to store charge of a capacitor 5.2 Ceramic Electrolytic Plastic film capacitors Silver mica Tantalum (any four) (2) (4) C T 1 1 C C = C T = 0,67 F Q T = CV = 0,67 x 100 = 67 µc Q T = Q 1 = Q 2 67 µc (2) 5.4 Draw neat, labelled IEC symbols for the following components:

17 5.4.1 (2) Anode Cathode (2) Anode Cathode Brown, Black, Brown (2) (2) (2) Orange, Orange, Orange (2) 5.6 Forward biased is when the positive (+) voltage is applied to the P- type and the negative (-) voltage is applied to the N- type material. The depletion region is decreased, making it easier for current to flow. (4) (30) TOTAL: [150]

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19 Electrical Technology DBE/November 2014 NSC