1. A tachometer is an instrument used to measure

(a) the prospective short-circuit current

(b) the linear speed of a vehicle

(c) rotational speed

(d) the force needed to drive home an earth spike

2.Most modern temperature-measuring systems rely on

(a) a low ambient temperature

(b) the thermocouple principle

(c) radiant heat from the subject

(d) a passive infra-red detector

3. A Schmitt-trigger circuit is used in an electronic frequency-measuring device to

(a) bring the measured frequency and the crystal output into phase

(b) convert the measured waveform to a square wave

(c) start the two signals at exactly the same instant

(d) act as an AND logic gate

4. The assembly in a cathode-ray tube which fires a stream of electrons at the screen is called the

(a) X plates (b) deflection assembly

(c) electron gun (d) cathode