Question

The conversion of heat into electrical energy may be achieved using:
(A) Hydrometer
(B) Thermocouple
(C) Voltmeter
(D) Photo-electric tube

Answer 1

Hint
Thermocouple is a device which measures temperature. It has two conductors which are in contact where the temperature differential is experienced. Thermocouple uses the seebeck effect where a solid-state device converts heat flux directly into electrical energy.

Complete step by step answer
The correct answer is thermocouple. They are used in measuring the temperature of a point relative to a different point. One side is placed in a hotter environment than the other and this difference in temperature generates electric current. This electric current is then measured with the help of a voltmeter or a microcontroller which converts the electric voltage to the temperature using a suitable format. Hydrometers are used for measuring the density of liquid. Voltmeter is used for measuring voltage difference between 2 points and a photoelectric tube converts energy from sunlight to electric energy by exciting the electrons and moving them.
The correct option is (B).

Note
Hydrometer is used for measuring relative densities of liquids. Voltmeter is an instrument used for measuring the potential difference across an electric circuit. Analog and digital voltmeters are used in laboratories to measure the electric voltage of the circuit. Photoelectric tube emits electrons when it is illuminated and has an anode to collect the emitted electrons.