Question

LED has been used rather than the normal bulb to test the conductivity of liquids justify the answer

Answer 1

In testing the electrical conductivity of liquid current flow is very low. when a current passes through a a bulb it's filament gets heated up and light. But the current flow in liquid is so low that it is not sufficient to light up a bulb.

LED on the other hand require very low amount of current to produce light. Hence they will glow even in very less current.

Hence LED is used to detect very low current which may not be noticed by a bulb.

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