Direction of Force On Wires
In this lab, we connect two wires to a power supply. The force due to the magnetic field from wire 1 on wire 2 and from wire 2 on wire 1 can be found by the definition of magnetic force and magnetic field.
We make few predictions whether the two wires will repel or attract to each other when they have same direction current or opposite direction. When the current in the wires has the same direction, we predict that the wires will attract each other by the right hand rule.
Our prediction is correct. We observe that the wires move towards each other. On a charged line, the magnetic field are created to be counterclockwise. On its left, the magnetic field is pointing out. On its right, the magnetic is pointing inward. Using the right hand rule, we can see that the forces are acting toward each other.
When the current in the wires has the opposite direction, we predict that the wires will repel each other by the right hand rule.
Again, our prediction is correct.
Magnetic Field Sensor (Solenoid)
In this lab, we use wires to bend into loops on the test tubes to form a coil. When we connect it to a power supply, it acts as an electromagnet, and it will generate a magnetic field. With LoggerPro, we can see that the magnetic field in a loop is proportional to the number of loops and the current running through the loops.
Set Up for the lab
In this lab, we use a magnetic field sensor to measure the strength of the magnetic field. We can get a max magnetic field in the end of the solenoid.
As seen in the picture above, the more loops we have, the higher the magnetic field is.
From this we get the formula for a magnetic field in a solenoid to be
Galvanometer
A galvanometer is used for detecting electric current. It can measure the inducted current.
This is what a galvanometer looks like.
We list the factors that can change the current induced in a coil.
After playing around with the coil, a magnet and the galvanometer, we can see that what effect current are: velocity of pulling out/pushing in, number of turns of the coil, magnetic field, and the area between the magnet and coil.
Lenzs’ Law: Aluminum and Plastic Tubes
For this lab, we put them through two tubes at the same time; one is made of aluminum and one is made of plastic. We predicted that when the magnetic object is dropped in the aluminum tube it would fall slower since it will product a force reject it to leave.
When we do the experiment, we find our prediction to be right, the magnetic object fall faster in the plastic tube and significantly slower in the aluminum tube. Lenzs’ law states that a magnetic field always opposes an induced magnetic field. The magnet induces a current when it moves through a coil (aluminum tube) and as a result, it will produce an upward force. When the magnetic object is placed in the plastic tube, both objects drop at the same time since it does not induce current.
Faraday: Ring
For this lab, we have an aluminum ring. When we increase the current flowing into it, the ring flies. This is a force acting on it. The current running through the coil creates a magnetic field in that ring, going up, and that magnetic field induces a current which creates another magnetic field going the opposite direction, down. The two magnetic fields are repelling each other which makes it fly. Also, it is warm because the current is running through it. Then, we place the ring with another ring with slit on it.
When it is connect to the power supply, nothing happens. Then, we put a coil with a light bulb to it. When we connect the larger coil with power supply, it will induce a current and lights up the light bulb.
Magnet and Rod:
In this lab, we will see how the current is affected with the area changing. Current is applied to the two rails. A large magnet is placed in between the two rails. We place an aluminum rod on the two rails.
When a current goes through the rod, there is a magnetic field in a circle around that rod. When there is a current, the rod moves since it has a force acting on it by the right hand rule. The area of the magnetic field will change. When the area gets larger and larger, we can get an induced current.
Measuring earth magnetic pole:
In today's lab, we use LoggerPro and the magnetic sensor to measure the earth magnetic pole. We connect logger pro to magnetic sensor and graph the picture as we moved around the classroom.
As the data shown in the following picture, we find the north side of the classroom which the sensor has the highest measurement. Therefore, we can conclude that the north of earth has the strongest magnetic field.
Summary:
In today's lab, we learn how to measure the magnetic field strength. We learn how induction and Lenzs' Law works. We practice to use right hand rule more.
No comments:
Post a Comment