Which of the following is correct for the charge in a magnetic field?
Choose one answer.
a. A stationery charge can experience a force in a magnetic field.
b. A moving charge parallel to the direction of the magnetic field can experience a force.
c. A moving charge perpendicular to the direction of the magnetic field can experience a force.
d. A moving charge parallel but opposite to the direction of the magnetic field can experience a force.
c. A moving charge perpendicular to the direction of the magnetic field can experience a force.
The correct answer for the charge in a magnetic field is option c. A moving charge perpendicular to the direction of the magnetic field can experience a force.
To understand how to get to the correct answer, we need to review the concept of magnetic fields and how they interact with moving charges.
When a charged particle, such as an electron, moves through a magnetic field, it experiences a force called the magnetic force. This force is perpendicular to both the velocity of the charge and the magnetic field. The magnitude of the force is given by the equation F = qvBsinθ, where F represents the force, q is the charge of the particle, v is its velocity, B is the magnetic field strength, and θ is the angle between the velocity and the magnetic field.
In option a, it is stated that a stationery charge can experience a force in a magnetic field. However, a stationary charge does not have a velocity (v = 0), and according to the equation above, the force will also be zero (F = qvBsinθ = q(0)Bsinθ = 0). Therefore, option a is incorrect.
In option b, it is mentioned that a moving charge parallel to the direction of the magnetic field can experience a force. However, according to the equation, when θ = 0° (the charge is moving parallel to the magnetic field), the sine function will be zero (sin(0) = 0). As a result, the force exerted on the charge will be zero. Hence, option b is also incorrect.
In option c, it states that a moving charge perpendicular to the direction of the magnetic field can experience a force. This is true because when θ = 90° (the charge is moving perpendicular to the magnetic field), the sine function will be equal to 1 (sin(90°) = 1). Thus, the force exerted on the charge will be nonzero. Therefore, option c is correct.
In option d, it mentions that a moving charge parallel but opposite to the direction of the magnetic field can experience a force. However, if the charge is moving parallel but in the opposite direction of the magnetic field, θ will be equal to 180°. In this case, the sine function will be zero (sin(180°) = 0), and the force will be zero. Hence, option d is incorrect.
To summarize, option c is correct: a moving charge perpendicular to the direction of the magnetic field can experience a force.