In the topic "polarity of voltage drops",the diagram showig the current direction is same as electron direction.How it can be possible?the direction of current would be opposite to the direction of electrons.

 

Conventional current flow is defined as being from positive to negative, i.e. against the flow electrons. Our forefathers felt this was the most intuitive model of current flow.

Actual current is the migration of charge (electrons being mobile negative charge) and consequently flow from negative to positive (negative electrons are attracted to a positive source). What you see in the above topic is actual current flow.

This should help: http://www.allaboutcircuits.com/vol_1/chpt_1/7.html

Dave

 

Current is the process of 2 different charges traveling in opposite directions. Technically, neither is wrong, so don't worry about it too much (although I prefer conventional due to it being the most popular standard to go by).