4.5.5 The d.c. motor (3)
Resources |
Revision Questions |
Physics
Login to see all questions
Click on a question to view the answer
1.
A coil is placed in a magnetic field. Explain how increasing the strength of the magnetic field will affect the magnetic turning effect on the coil. Include a relevant equation in your answer.
The magnetic turning effect on a coil is directly proportional to the strength of the magnetic field. This is because the magnetic force on a single loop of wire is given by F = BIlsinθ, where B represents the magnetic field strength.
As the magnetic field strength B increases, the magnitude of the magnetic force on each loop of wire increases proportionally. This increased force results in a greater torque being applied to the coil, leading to a larger turning effect. Therefore, increasing the magnetic field strength will increase the magnetic turning effect.
2.
State three factors that affect the force experienced by a current-carrying conductor in a magnetic field. Explain how each factor influences the magnitude of the force.
Three factors that affect the force experienced by a current-carrying conductor in a magnetic field are:
- The magnitude of the current (I): The force is directly proportional to the magnitude of the current. A larger current means more charge carriers are moving, resulting in a stronger magnetic field produced by the current and therefore a greater force.
- The strength of the magnetic field (B): The force is directly proportional to the strength of the magnetic field. A stronger magnetic field exerts a greater force on the moving charges.
- The length of the conductor within the magnetic field (l): The force is directly proportional to the length of the conductor within the magnetic field. A longer conductor experiences a greater force because more of its length is exposed to the magnetic field.
3.
A coil carrying a current is placed in a magnetic field. State how the magnetic turning effect on the coil changes if the current flowing through the coil is increased. Explain your answer.
The magnetic turning effect on a coil is directly proportional to the current flowing through the coil. This is because the magnetic force on a single loop of wire is given by F = BIlsinθ. Here, I represents the current.
As the current I increases, the magnitude of the magnetic force on each loop of wire increases proportionally. This increased force results in a greater torque being applied to the coil, leading to a larger turning effect. Therefore, increasing the current will increase the magnetic turning effect.