Q28 of 76 Page 271

What is the advantage of using LED in testing the electrical conductivity of liquids ?

The advantage of using LEDs is because, they glow up even if very small amount of current passes through them.

Which of the following liquids conduct electricity and which do not conduct electricity?

Lemon juice, Milk, Vinegar, Common salt solution, Sulphuric acid solution, Sugar solution, Distilled water, Honey, Sea water, Rainwater.

Why is it dangerous to touch a working electrical appliance with wet hands?

Which effect of electric current is utilized for detecting the flow of current through a solution:

(a) when a torch bulb is used?

(b) when a compass is used?

What happens to the needle of a compass kept nearby when electric current is switched on in a wire? Why does this happen?