Question 7
- Define the term transducer
- State the energy transformation that exist in the following transducers:
(i) tachogenerator;
(ii) piezo-electric crystal;
(iii) photo voltaic cell;
(iv) loudspeaker;
(v) phono graphic pick-up;
(vi) motor;
(vii) thermocouple;
(viii) microphone.
The expected responses were:
(a) A transducer is defined as a device that converts energy from one form into another.
(b) Energy transformation in transducers
(i) Tachogenerator: converts angular speed (or velocity-mechanical energy) into voltage (electrical energy).
(ii) Piezo-electric crystal: converts mechanical strain (or pressure-mechanical energy) into voltage electrical energy)
(iii) Photo-voltaic cell: converts light energy into electrical energy
(iv) Loudspeaker : converts electrical energy into sound (mechanical energy)
(v) Phono graphic pick-up needle: converts mechanical vibrations into sound energy
(vi) (Electric) Motors: converts electrical energy into mechanical energy. (Vehicular motors essentially convert chemical energy into mechanical energy.
(vii) Thermocouples: converts temperature difference (heat energy) into voltage (electrical energy)
(viii) Microphones: converts sound energy into electrical energy.
The Chief Examiner reported that, overall, majority of the candidates that attempted this question responded well while only a few could not state the energy transformation that exist in piezo-electric crystal and phonographic pick-up.