2021 S4 SST Prelim

Page 1 of 26 [Turn over SECONDARY 4 PRELIMINARY EXAMINATION ELECTRONICS 6063/1 25 August 2021 (Wednesday) 2 hours CANDIDATE NAME CLASS INDEX NUMBER READ THESE INSTRUCTIONS FIRST Do not turn over the page until you are told to do so. Write your name, class, and index number in the spaces provided above. Write in dark blue or black ink pen. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, and glue or correction fluid/tape. Sections A and B Answer all the questions. Write your answers in the spaces provided on the question paper. Approved electronic calculators are allowed for use in this paper. The number of marks is given in brackets [ ] at the end of each question or part question. The total marks for this paper is 100. This document consists of 26 printed pages including the cover page FOR EXAMINERS’ USE Section A / 38 Section B / 57 TOTAL / 95

Page 2 of 26 [Turn over Resistor Colour Code

Page 3 of 26 [Turn over Table on Boolean algebra

Page 4 of 26 [Turn over Section A Answer all questions. Write your answers in the spaces provided. 1 Pulse Width Modulation (PWM) can be used to transmit data in telecommunications. Fig. 1.1 shows how the message signal (X) is modulated with carrier signal (Y) to produce PWM signal (Z). Fig 1.1 (a) State the type of signal shown in Fig. 1.1 in the table below. [2] Signal Type of signal X Z (b) State the difference between carrier signal (Y) and PWM signal (Z). [1] ......…..……………………………………………………………………………………... ......…..……………………………………………………………………………………... [Total: 3 marks]

Page 5 of 26 [Turn over 2 Fig 2.1 shows a common emitter amplifier that is commonly used to amplify signal from sources such as microphone or photodiode sensor. Fig. 2.1 (a) (i) Deduce the output KVL equation. [1] (ii) Calculate VC if IE = 1.5 mA. [1] Vc =……………………….……… (b) Determine the base current IB. [1] ..………………………………………………..…..………………………………………. (c) Determine the gain of the amplifier.