A train of 150 m length is going towards north direction at a speed of 10 ms-1. A parrot flies at a speed of 5 ms-1towards south direction parallel to the railway track. The time taken by the parrot to cross the train is equal to
The unit of electric current 'ampere' is the amount of current flowing through each of two parallel wires 1 m apart and of infinite length will give rise to a force between them equal to