Lab 22: Electromagnetic Induction

We started the day by doing an experiment that consisted on using a magnet, a rod and two metal plates. The arrangement was set as in the picture below. Given that the magnetic field is going upwards, professor Mason send a current going counterclockwise through the rod. The result of this caused a magnetic force on the rod that push it away from the magnet. And as the rod is getting away from the magnet, the area of the loop increase over time.

We predicted that the rod was going to move away from the magnet by using the right hand rule as we already know that  F = ILxB. Since the current is going counterclockwise and the magnetic field is going upwards, then there is a resultant force acting on the left direction.

Professor Mason repeated the experiment by reversing the direction of the current. Applying the right hand rule, there is a force acting on the rod that pulls it towards the magnet, and as it moves closer to the magnet, the area of the loop gets smaller over time.

 Then we start working on the electromagnetic induction simulation from active physics. This simulation allowed us to learn more about magnetic flux and induced emf.

 In this picture, we derived inductance in terms of number of loops, permeability, area of loops and length of inductor. We started with the formula L = emf / (dI/dt), the length of the inductor equals the emf produced by the inductor over the rate the current changes in the inductor, we solved for emf. Then we used another formula that is emf = -(d/dt)(magnetic flux). And we know that flux is NBA. We used B = ((permeability)(current)(number of loops))/ length. Then we equate each emf and solve for the inductance.

 In this picture we applied the derived formula and solve a problem with given variables. Also, we derived the units for inductance using SI units.

 We worked on another active physics activity that consisted of RL Circuits. In this activity we learnt that I = Imaxe^(-t/τ), where τ is the time constant. Also as inductance increases, then it takes longer time for the current to reach equilibrium, τ ~ L. Also, as resistance increases, then it takes less time for the current to reach equilibrium, τ ~ 1/R. Then we can say that τ = L/R.