A heavy conductor (mass m, length `, resistance R) is suspended by two springs each with spring constant k, and connected to a battery with electric potential V as shown in
the figure. A magnetic field ~B is now imposed. The acceleration of gravity is 9.8 m/s2 .
Which direction should the magnetic field point to have the most effect in raising the heavy conductor?
1. Out of the page
2. Into the page
3. Vertically downward in the plane of the page
4. The direction of the magnetic field is irrelevant.
5. To the left in parallel to the the conductor
6. Vertically upward in the plane of the page
7. In the plane of the page at a 45 degree angle to the conductor
8. To the right in parallel to the conductor
The key is the direction of the current, and the direction of B in relation to the conductor.
Still not sure here is the sketch...
---------- + - -------
| V |
| |
Spring K Spring K
| |
| |
<----------l--------->
Heavy Conductor R
|
mg
Hope this helps! Please help.
I selected #1 AND IT WAS INCORRECT. I guess I just don't understand...
To determine the direction in which the magnetic field should point to have the most effect in raising the heavy conductor, we need to consider the interaction between the magnetic field and the current flowing through the conductor.
First, let's establish the direction of the current in the conductor. Looking at the sketch, the battery is connected to the conductor, indicating that there is a source of electric potential causing a current to flow. Since the battery is supplying power to the conductor, the current will flow from the positive terminal of the battery to the negative terminal. Following the convention, this indicates that the current flows from left to right in the conductor.
Next, we need to consider the interaction between the current and the magnetic field. According to the right-hand rule, when a current-carrying conductor is placed in a magnetic field, the direction of the force on the conductor is perpendicular to both the current direction and the magnetic field direction.
In this case, as the conductor is hanging vertically, the force due to gravity is acting downward. To counteract this force and raise the conductor, we need the net force on the conductor to be in the upward direction.
To achieve this, we need the force due to the interaction between the current and the magnetic field to be in the upward direction. This can be achieved when the magnetic field is directed into the plane of the page (option 2: Into the page).
Therefore, the magnetic field should point into the page to have the most effect in raising the heavy conductor.