Suppose that the lab wiring is mistakenly designed so that all the stations are on the same 120Volt circuit. A circuit breaker allows a maximum of 40Amps to be drawn by the lab stations. If each lab station used 550watts or power how many lab stations can be running at once before the circuit breaker cuts off the power

9 stations .

Explanation:

All the stations are connected in parallel .

volt at each station =  120 V .

power used at each stations = 550

power = volt x current

550 = 120 x current

current = 4.5833 A

maximum current allowed by circuit breaker = 40 A

no of lab stations possible = 40 / 4.5833

= 8.72 or 9 .

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