Moving Charges And Magnetism

Reading of voltmeter
... (i)
If resistance is increased to , the reading of voltmeter,
(Using (i))

The radius of the circular path, of a charges particle in magnetic field

Here, kinetic energy for proton and helium is same and both are moving in the same magnetic field

So,

A current flows in a straight wire from point A to B. According to electromagnetic theory, the electric current does not flow in the nearby circular path unless it is part of the conducting circuit. Therefore, no actual current flows in the circle.

The magnetic field at the center of a uniformly charged circular loop with current is given by: The force on a charged particle moving with speed in a magnetic field is given by: where because the particle moves along the axis of the circular loop, making the angle between the velocity and the magnetic field direction . So, the force becomes: At the center of the loop, the magnetic force is zero because the magnetic field at the center of the loop is directed along the axis and the velocity is also along this axis. Hence, the magnetic force is zero. Thus, the correct answer is (D).

The average force on each electron due to the magnetic field is given by: But we need to express this in terms of current and geometry of the coil. Let’s break it down:
Given: - Number of turns
- Radius
- Magnetic field
- Current
- Charge of electron
Let total length of the wire in the coil be
Drift velocity , but we avoid calculating that directly. Instead, we use the concept of Lorentz force acting on a single charge moving in a magnetic field. The average force on an electron in a current-carrying conductor is: Now, number of electrons per unit volume and area is assumed standard for copper, but we take final value from approximation: Using: Putting approximate constants, we get:

The magnetic moment of a current-carrying coil is given by: where is the area enclosed by the coil. For a regular hexagon, the area is: Thus, the magnetic moment is: Thus, the correct answer is (A).