As the external magnetic field decreases, an induced current flows in the coil. what is the direction of the induced magnetic field caused by this current?

As the external magnetic field decreases, an induced current flows in the coil. The direction of the induced magnetic field would be pointing to the screen. The flux through the coil is said to decrease. In order to counter this change, the coil would generate or produce a magnetic field that is induced that would be pointing to the same direction as the external field that is flowing which is into the the screen. This is according to Lenz's law or the right hand rule. It states that an induced current in a circuit that is due to the change or motion in   magnetic field should be directed opposing to the change in the flux.

Answer(a)   the matererials that are in contact, the two materials and the nature of their surfaces/// (b)/// the force pushing the two surfaces together, pushing the surfaces together causes the more of the asperities to come together and increases the surface area in contact with each other