This time, each magnet is now attracted to the iron plate, and don't see the other magnet on the other side of the plate, even though both of the North poles are facing each other! The diagram on the right shows what happens if you insert a superconductor between the magnets. Now, each magnet is repelled by the superconductor, and there is little or no attraction between the magnets themselves (one little field line did sneak around the superconducting plate, though).
Cardiac muscle (heart muscle) This type of muscle is found solely in the walls of the heart. It has similarities with skeletal muscles in that it is striated and with smooth muscles in that its contractions are not under conscious control. However this type of muscle is highly specialised.
Smooth muscles take longer to contract than skeletal muscles do, but they can stay contracted for a long time because they don't tire easily. Cardiac (pronounced: KAR-dee-ak) muscle is found in the heart. The walls of the heart's chambers are composed almost entirely of muscle fibers. Cardiac muscle is also an involuntary type of muscle.