Question

State and explain for each case whether the information given by the following devices is in analogue or a digital form.
a moving-coil voltmeter measuring the e.m.f. of a cell, a microphone generating an electric current, a central heating thermostat controlling the water pump, automatic traffic lights controlling the flow of traffic.

Answer 1

Ans. (a) The e m.f. of a cell can either be measured by an analogue voltmeter or a digital voltmeter. Hence, e.m.f. can be either analogue or digital quantity.
(b) The current in the microphone varies according to the variation in sound pressure Since this variation is continuous, hence current from microphone is an analogue quantity
(c) A central heating thermostat regulates the heating system consistently to maintain the desired temperature of the room. When room temperature falls below the fixed temperature, the thermostat switched ON the central heating and when the desired temperature is reached, it switches it OFF again. So, thermostat is essentially a switch which turns the heater ON or OFF as needed and is a digital system. '
(d) The digital circuits used in traffic control light system makes them ON or OFF. Hence, automatic traffic lights is a digital system.