10.9 Applications
Application: The Magnetic Brake An interesting and very useful application of induced currents is the magnetic brake.
To outline the principle involved, consider Figure 10.21a. An electromagnet generates a flux density B in the gap. This field
is assumed to be constant. A pendulum-like flat piece, made of a conducting material, is placed such that it can move into the
gap. If the current in the electromagnet, I, is zero, the oscillation of the pendulum is not affected by the structure. If there is a
current in the coil, the movement of the conducting plate into the magnetic field (Figure 10.21b) generates induced currents
in the plate itself due to the motion of the conductor in the magnetic field. The flux of the induced currents is such that it
opposes the field B. According to Lenz’s law, the induced currents tend to maintain this condition by opposing the flux.
Figure 10.21b gives the direction of the fields. The electric field intensity due to the induced currents is given as E ¼ v B
and we get