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# Tag Archives: Conducting

## Electricity field intensity within a conductor is always zero.Why?

Electricity field intensity within a conductor is always zero.Why?

The main difference between a conductor and an insulator is that the conductors contain plenty of free electrons which are free to move throughout the conductor; whereas the insulators do not have free electrons at room temperature.

When a conductor is held in an electric field, the free electrons inside them instantly drift opposite to the direction of electric field until the electric field due to the drift balances the external electric field and the net electric field inside the conductor becomes zero.

## Why there are Sine functions in Physics?

Why are sine functions used in some of the equations in physics?
For example,in the expression for instantaneous emf induced in a rotating conductor placed in an uniform magnetic field which is given by
E=B*L*V*sin(theta)
where,
B is the strength of the magnetic field,L is the length of the conductor and (theta) is the angle between the direction of motion of the conductor and the magnetic field,and here,my question is why do we use sine function in this expression?what is its need?

The function sin (theta) in a right angled triangle = opp. side /Hypotenuse

When we have to take a component perpendicular to another, we take the sine function.

## Why is the force on a wire NOT carrying current is zero when kept in a magnetic field?

Explain zero force acting on a wire  which is not carrying current,on being placed inside a magnetic field.

A charge at rest will not experience any force in a magnetic field, but a moving charge will experience  a force unless it is moving parallel to the field.

In a conductor, the electrons are in rapid and random motion, but the conductor will not experience a force until a current is passing through it. (Even though the electrons are not at rest). This is because, in the absence of a current, the motion of electrons is random and there is no net drift of electrons in any direction. Thus the forces cancel out.

When a current is passed through the wire, there is a net drift and hence a net force is experienced by the current carrying conductor in a magnetic field.

Further, I want to mention that the force is experienced between the existing field and the field produced by the moving charges/ current.

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