Question

The right hand thumb rule is used to find the:
(A) Force on a charged particle passing through the magnetic field
(B) Force on a current carrying conductor placed in a magnetic field
(C) Direction of induced current.
(D) Direction of magnetic field around a current carrying a straight conductor.

Answer 1

The right hand thumb rule is derived from Fleming's right hand rule. The right-hand rule of Fleming indicates the direction of the induced current as a conductor in a magnetic field passes connected to a circuit. It may be used to evaluate the current direction in the windings of the generator.

Complete step by step answer:
-Right hand thumb rule states that “If the current carrying conductor is carried in the right hand by pointing the thumb finger towards the direction of the current flow and the other fingers curled around the conductor, the curled fingers indicate the direction of the magnetic field due to the current carrying conductor. This law only shows the position of the magnetic field of the current conductor.
Right hand thumb rule is used in applications of Ampere’s circuital law:
i) The electrical current flows through the solenoid, resulting in a magnetic field. When you curl your right hand around the solenoid with your fingertips in the direction of the traditional current, your thumb points towards the magnetic North Pole.
ii) The electrical current travels through a straight cable. Here, the thumb points in the direction of the traditional current (from positive to negative) and the fingers point in the direction of the magnetic flux lines.
-The theory is often used to describe the position of the torque vector. If you hold the imaginary axis of rotation of the rotation force such that the fingers point in the direction of the force, then the stretched thumb points in the direction of the torque vector.

The right hand thumb rule is used to find the direction of magnetic field around a current carrying a straight conductor. Hence, option D is correct.

Note: The right hand thumb rule may be confused with Fleming’s right hand rule. But Fleming’s right hand rule is different from the right hand thumb rule. Fleming’s right hand rule gives the position of charge also.