Firstly,when inductor opposes the current from rising still the
current rises although less steeply,why is it so?
The inductor doesn't oppose current, it induces a voltage that opposes the rate of change in current.
The relationship between the current in and voltage across an inductor is given by
From the equation you see that the greater the rate of change in current, the greater the induced voltage that opposes that change.
See diagrams below. Let's say the current is the sine wave, then the induced voltage is the cosine. Note at time = 0 the value of the cosine is maximum in opposition to the supply voltage when the sine is zero but its rate of change (slope) is maximum positive, meaning the induced voltage opposes the change in current. As the slope of the sine decreases (i.e., its rate of change decreases) the induced voltage decreases in opposition to the supply voltage.
Secondly, we know the inductor induces an emf but between which two
point does this voltage exist?
The emf is across the ends of the inductor as shown in the diagram.
given this opposition in change of current from inductor why the
current still manages to change?
Because an inductor resists a change in current, it does not prevent it.
An inductor with a constant current produces a magnetic field. That magnetic field represents stored energy in the inductor, in this case, in the form of kinetic energy. (A capacitor has stored energy in the electric field between the plates and, in that case, the stored energy is electrical potential energy). Perhaps the following mechanical analogy will help.
Now think of a mass moving at constant velocity and having kinetic energy. It will resist any attempt to slow it down (reduce its kinetic energy) or speed it up (increase its kinetic energy) analogous to an inductor resisting any attempt to change its current (and thereby changing the kinetic energy of its magnetic field). The mass has inertia. The inertia (to current change) of an inductor is analogous to the inertia (to velocity change) of the mass. The analogy can be seen when one compares faradays law of induction.
With Newtons's second law of motion
Very roughly speaking, we can consider:
- Voltage as the analogue of force
- Inductance as the analogue of mass
- Velocity as the analogue of current.
I would like to stress that inductance is not mass, velocity is not current, and voltage is not current. The analogy is simply intended to help you get some feel as to what is going on.
Hope it helps