how can there be a cureent flow when back emf equal and opposite of suuply voltage?Isnt there a cancellation of voltage to zero volt?i have attached a video regarding this.Please answer this intuitively,i have already wasted enough time on this but couldnt find satisfactory answer. https://www.youtube.com/watch?v=ae0fy435zJA
Voltage across an inductor rules rate of change of current, not its value.
i.e. voltage across is zero? then current do not change, what was it befor? 1A? Okay it stays at 1A constant.
The back EMF actually is equal and opposite of supply only at the moment the supply is connected to an inductor that was without current before.
After that it more or less slowly dereases and current starts to flow.
The voltage applied to a coil cannot be cancelled with the coil voltage. The coil voltage is EQUAL to the applied voltage.
Think of current in an inductor as having inertia.
You need to apply a large force (voltage) to accelerate an inertial mass like a car (or increase current flow), and the only way to stop it once it's moving and has gained momentum, is to apply a large opposing force (voltage) like the brakes.
Attempting to stop it suddenly with a brick wall (or opening a switch) results in large and possibly destructive forces (or a high voltage spike).