CSEC Industrial Technology Paper 2 May/June 2021 - Free CXC Past Paper with Answers

In the spaces provided, draw a standard electrical/electronic symbol of the components listed.

• (i) DC voltmeter
• (ii) Zener diode
• (iii) Electric bell
• (iv) J-K flip-flop
• (v) AC motor
• (vi) Double-pole single-throw switch

DC voltmeter

Zener diode

Electric bell

J-K flip-flop

AC motor

Double-pole single-throw switch

A modulator combines a radio frequency carrier signal with an audio frequency signal to transmit information over a long distance. In the spaces below, sketch the output signal of a modulator that varies

• (i) the frequency of the carrier signal
• (ii) the amplitude of the carrier signal.

Figure 1 shows a pictorial diagram of an electronic circuit.

Figure 1. Electronic circuit

Draw, in the space below, a schematic diagram to represent the circuit shown in Figure 1.

Identify TWO non-renewable sources of energy used by power generating stations.

Identify TWO renewable sources of energy used to generate electricity.

State TWO types of internal losses in a power transformer, other than eddy current losses.

Describe how eddy current losses in a transformer may be minimized.

Draw a simple sketch to show how THREE single-phase power transformers may be connected to form a three-phase Star (WYE) transformer.

For a given series RLC circuit, where $R = 33\ \Omega$, $C = 10\ \mu F$, $L = 50\ \text{mH}$, $V = 75\ \text{V}$, and $f = 200\ \text{Hz}$, calculate the (i) impedance, $Z_T$, of the circuit (ii) phase angle, $\Theta$, of the circuit.

impedance, $Z_T$, of the circuit

phase angle, $\Theta$, of the circuit.

List THREE reasons for conducting EACH of the following tests and checks on a complete installation.

Visual inspections

Continuity tests

Outline the procedure for conducting a polarity test on a complete electrical installation that is NOT connected to an electrical supply system.

Outline ONE procedure for conducting a polarity test on a complete electrical installation that is connected to an electrical supply system.

With the aid of labelled diagrams, show the relationships between the

• phase ($V_{ph}$) and ($V_L$) voltages
• phase ($I_{ph}$) and line ($I_L$) currents in EACH of the following:

Three-phase, three-wire delta-connected secondary winding of a power transformer

Three-phase, three-wire, Star (WYE) connected secondary winding of a power transformer

The p-n junctions of any transistor may be biased to operate in three modes (or regions).

List EACH of the three modes of operation.

Identify the biasing criterion for EACH mode of operation listed in (a) (i).

Sketch a simple common-base transistor configuration, labelling the input and output terminal points.

Draw a simple sketch to show the phase relationship between the input voltage ($V_i$) and output voltage ($V_o$) of the common-emitter transistor configuration.

The truth table for a TWO input logic gate system is shown below.

Complete the truth table for the expression $(A \cdot B) + (A+B)$.

Sketch the simplest logic circuit diagram for the expression $(A \cdot B) + (A+B)$.