Confusion regarding Faraday's law Suppose we have a rectangular coil placed in a uniform magnetic field and the coil is rotated at a uniform speed. Now, we know that due to the change in the magnetic flux linked with the coil that an induced current flows. What is the force responsible for this? Is it the magnetic force or the electric force? If it is the magnetic force, then is there any electric field produced and thus a potential gradient (I mean similar to the potential gradient we have in case of a simple DC circuit)?
 A: Note first that there will be no current unless the ends of the coil are joined together, perhaps by an external resistive load.
The force giving rise to the current is the is the magnetic Lorentz force ($\vec F=q \vec v \times \vec B$) acting on free electrons in the two sides of the coil that are cutting magnetic flux.
Now to address your question, "is there any electric field produced and thus a potential gradient (I mean similar to the potential gradient we have in case of a simple dc circuit)?" Yes: in the two sides of the coil that are not cutting magnetic flux, and in the external load, the free electrons are forced through the wire by an $electric$ field arising from an imbalance of charge due to the (magnetic) e.m.f. described in the previous paragraph. 
[Note that the electric field just discussed arises only indirectly from the cutting of magnetic flux. It is not an electric field arising from a changing magnetic field according to the Faraday-Maxwell equation, $\text{curl} \vec E =-\frac{\partial \vec B}{\partial t}$, for the simple reason that $\frac{\partial \vec B}{\partial t}=0$.]
A: The rotating coil with a changing magnetic flux linked with it has an electric field induced in it - Faraday’s law.  
If there is a complete electrical circuit an induced current flows in the coil because of the induced electric field.  
The direction of the induced current and the resulting magnetic field produced by the induced current is such as to oppose the change in the magnetic flux producing it - Lenz.  
The induced current interacting with the applied magnetic field produces a force on the coil - Lorentz.
This force does not exist if there is no induced current even if there is an induced electric field, ie if there is a break in the coil.
That force will try and slow down the rotation of the coil if there are no other forces acting on the coil.  
In terms of energy the kinetic energy of the coil is converted to heat - Ohmic heating due to the coil having resistance and a current passing through the coil.  
If the coil is to maintain a constant speed of rotation then there must be an external forces/torque doing work on the coil.
