is a.c

If you are going to post on here at least try posting a sensible question.

Sounds like homework!

1) Standing before a approaching diesel loco powered train or Electric loco powered Train which is more dangerous?

2)Fan does not .U do it using the regulator

3)Pl. refer old threads of this forum

4)Now that I have answered 3 questions why don't u try the 4th as home work?

1. DC does not pass through zero and hence we are likely to get sever shock as compared to AC, which passes twice through zero in each cycle, of equivalent voltage.

2. There are two types of regulator for controling fan speed. The conventional one is a variable resistance across which full voltage is dropped and the variable voltage is applied to fan. The electronic regulator consists of SCRs whose firing angle is controlled and it regulates the effective voltage applied to fan.

3. Transmitting electricity at higher voltages (132kV, 300kV and so on) is not economical. But generating voltages at these voltages is not economical and practically possible because of insulation considerations and bulky generators. 3.3kV, 6.6kV, 11kV are most economical voltages. Voltage is then stepped up to transmitting voltages thru Transformers.

4. Ideally Neutral voltage is zero (which is vectorial addition of three phase voltages). Also in majority of the cases neutral is earthed. We get a shock when current passes through our body (not when we touch conductor through which current is passing) which is possible only when there is voltage difference between our body and the conducting body which we touch.