Use Biot-Savart Law to derive the expression for the magnetic field on the axis of a current carrying circular loop of radius R.
Draw the magnetic field due to a circular wire carrying current I.
Consider two small current elements on the circular loop which are opposite to each other.
then the magnetic field at a point p which is at a distance X from the centre of the coil is due to the component of the fields of A and B and y components cancel out.