An industrial overhead door has a chain and sprocket system designed to reduce the force needed by an operator to open and close the door. the system consists of two individual systems that are connected through a live axle shaft. to operate the door, the operator pulls a continuous loop of chain over a fixed 22 tooth sprocket that is attached to a live axle shaft. the second 22 tooth sprocket is attached to a drum that drives the door. what is the overall system ratio?

where is the photo and the answer choices?

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia

option number c is the right answer.