sorry i do know this is not in syllabus of IITJEE.but for AIEEE

1) what is angle of declination?as i have read it in hc verma it is angle betⁿ mag meridian and geographical meridian. So my question is that is magnetic poles a circle or else there would be one circle on earth surface where there is no angle of declination. plz reply

This is in the syllabus of both the exams.

The declination of the sun is the angle between the equator and a line drawn from the centre of the Earth to the centre of the sun. The seasonal variation of the declination angle is shown in the animation below.

The declination angle, denoted by δ, varies seasonally due to the tilt of the Earth on its axis of rotation and the rotation of the Earth around the sun. If the Earth were not tilted on its axis of rotation, the declination would always be 0°. However, the Earth is tilted by 23.45° and the declination angle varies plus or minus this amount.