Choose the correct answer statements from the following:

A. Magnetic field lines due to a straight wire carrying current, are circles concentric with the wire.
B. Bohr magnetron is the maximum value of the magnetic moment of an electron moving around the central nucleus.
C. Ampere's circuital law is not independent of Biot-savart law.
D. Dip is the angle that the total magnetic field of the earth makes with the surface of the earth.

Choose the correct answer from the options given below:

A, C and D only

The correct answer is Option (4) → A, C and D only

(A) The magnetic field around a straight current carrying conductor forms concentric circles centered on the wire, as per ampere's law and right hand rule.

(C) Ampere's circuital law can be derived from the Biot-savart law. Hence, ampere's law is not independent and is essentially a special case for Biot-savart law.

(D) Magnetic Dip (or inclination) is the angle between the earth's magnetic field and the horizontal surface of the earth at a given location.