electric shock

Q:would the person receive electric shock if he puts his finger at the place indicated by the arrow?

A: Assume the person stands on ground, he would get an electric shock in all cases except in diagram 4.

In diagram 4, the point of touching is at earth potential. There is no potential difference between the person's finger and his body. Hence, no current would flow through his body.

Q: are there any criteria for electric shock to occur?

A: An electric shock occurs when there is a potential difference established between any two part of its body. This leads to an electric current flowing through the body.


2014-12-05 16:21:02 補充：
Q: why is no electric shock received in (d)?
A: I wonder if the answer marked in the question paper is correct.
Unless the person wears a pair of rubber shoes and is isolated from touching the ground, he would still receive an electric shock.

2014-12-05 16:28:14 補充：
(cont'd)...
There is bound to be moisture present on the floor in a bathroom. By standing with bare feet on the wet floor, the person has, in fact, got himself earthed. That said, his body is kept at earth potential....

2014-12-05 16:30:20 補充：
(cont'd)...
When he touches one of the wires, the potential difference between the wire (at 220 or 110 v)and his body (at 0 v) produces a current to pass through him, thus giving him a shock.