Magnetic Field

The particle that cannot be accelerated by a cyclotron is electron.

Gauss is the unit of magnetic field

Step 1: Formula for Force on a Current Element
The force on a current element in a magnetic field is given by the formula: Where:
is the force,
is the current,
is the length of the current element,
is the magnetic flux density,
is the angle between the magnetic field and the direction of the current.

Step 2: Given Values
(current),
(length of current element),
(magnetic flux density),
Assuming (since the angle is not specified, we assume the field is perpendicular to the current).

Step 3: Calculation
Using the formula:
Step 4: Conclusion
Thus, the force due to the current element is 1.2 N.

Step 1: Magnetic Field Due to a Circular Coil
The magnetic field at the center of a circular coil carrying a current is given by the formula: Where:
is the magnetic field,
is the permeability of free space,
is the current,
is the radius of the coil.

Step 2: Conclusion
From the formula, we can see that the magnetic field at the center of the coil is directly proportional to the current and inversely proportional to the radius .
Therefore, the correct answer is that the field is directly proportional to .

Step 1: Understanding the Behavior of a Coil in a Magnetic Field
When a coil carrying a current is placed in a uniform magnetic field, it experiences a torque due to the interaction between the magnetic field and the current in the coil.
The torque tends to rotate the coil to align it with the magnetic field.
Step 2: Why Other Options are Incorrect
Option (a) is incorrect because an emf is not produced simply by placing the coil in a uniform magnetic field.
An emf is generated when there is relative motion between the coil and the magnetic field or if the field changes with time.

Option (c) is incorrect because no net force is produced on the coil in a uniform magnetic field.
The force acting on opposite sides of the coil cancels out, leaving only torque.

Option (d) is incorrect because while torque is produced, there is no net force in a uniform magnetic field.
Step 3: Conclusion
Thus, the correct answer is that torque is produced when a current-carrying coil is placed in a uniform magnetic field.