I guess the answer is: B. rheostat
Please correct me, if I made a mistake.
Rheostat is an adjustable resistor used in applications that require the adjustment of current or the varying of resistance in an electric circuit. The rheostat can adjust generator characteristics, dim lights, and start or control the speed of motors. Its resistance element can be a metal wire or ribbon, carbon, or a conducting liquid, depending on the application. For average currents, the metallic type is most common; for very small currents, the carbon type is used; and for large currents the electrolytic type, in which electrodes are placed in a conducting fluid, is most suitable. A special type of rheostat is the potentiometer, an instrument that measures an unknown voltage or potential difference by balancing it, wholly or in part, by a known potential difference. A more common potentiometer is simply a resistor with two fixed terminals and a third terminal connected to a variable contact arm; it is used for such purposes as a volume control in audio equipment.
For the explanation given above rheostat is not an energy source.
Solar Cell - Assemblies of solar cells are used to make solar modules which generate electrical power from sunlight.
Battery - It is a device consisting of two or more electrochemical cells that convert stored chemical energy into electrical energy. Each cell contains cathode and anode. Electrolyte allows ions to move between electrodes and terminals which allows current to flow out of battery to perform work
Generator - It is a device that converts mechanical energy obtained from an external source into electrical energy as output.
Rheostat - It is a variable resistor which is used to control current. They are able to vary the resistance in a circuit without interruption. It uses only two connections, first connection is made to one end of resistive element and other connection to the wiper (sliding contact). Rheostats were often used as power control devices for example to control light intensity (dimmer), speed of motors, pumps, x-ray device, heaters and medical apparatus.
Generator, solar cell, battery are act as energy source but rheostat is not an energy source so answer is B
- Badges
- Science topic