Question

Fleming’s right hand rule is used to determine the direction of force acting on a current carrying wire placed in a magnetic field.
(A). True
(B). False

Answer 1

Direction of force is related to the direction of current in the conductor and the direction of magnetic field. That is why a simple rule can be used to describe its direction. The magnitude of the force varies with the angle between the direction of current and applied magnetic field.
Formulas Used:
$F=IlB\sin \theta$

Complete answer:
When a current carrying conductor is kept in an external magnetic field, a force acts on it which is perpendicular to the plane of magnetic field and the current. The force is given by-
$F=IlB\sin \theta$
Here
$I$ is the current in the conductor
$B$is the magnitude of the magnetic field
$\theta$is the angle between the direction of flow of current and the applied magnetic field
The direction of force acting on the current carrying conductor is given by- Fleming’s Left Hand Rule. It states that when you hold your left hand in such a way that your forefinger, middle finger and thumb are perpendicular to each other then, if your forefinger represents the direction of the magnetic field, the middle finger represents the direction of current; the thumb will give the direction of force.
Since the direction of force on a current carrying conductor placed in a magnetic field is given by Fleming’s Left Hand Rule, the question statement is false.

Hence the correct option is (B).

Note:
For a force to act on the current carrying conductor in a magnetic field, the angle$\theta \ne {{0}^{o}}\,or\,{{180}^{o}}$. The magnitude of force will be maximum when$\theta ={{90}^{o}}$. This force has various applications and can be used to convert electrical energy to work. Also, current can be induced in a conductor when it is moved in an external magnetic field.