Question

Father and a son returned home completely drenched due to heavy rain. Father advised his son not to touch any electrical units with wet hands for he may get a shock. In spite of this, on immediately entering the house, the son switches on the light (supply voltage is 220 V) and gets a severe shock. He was fortunate not to get electrocuted. Father; who is a Biologist, told that when the skin is dry, resistance of a human body is 105 ohm, and when the skin is wet the body resistance is 1500 ohm.

(i) What is the lesson learnt by you ?

(ii) Calculate the current that flow through

(a) a wet body and

(b) a dry body, and

(c) dry skin or wet skin.

(iii) When will we have serious consequences and why ?

Answer 1

(i) To obey elders.

(ii) Using, I = V/R,

(a) 147 mA;

(b) 2.2 mA

(c) Wet skin with 147 mA

(iii) When the current flows, the result is fatal.