What two base quantities are used to measure speed

The base quantities that are used to measure speed are distance and time.

Explanation

In quantitative calculation, speed of an object can be measured by knowing the distance traveled in a given time.

S= D/T

The distance is the actual stretch covered by the object.

The SI unit of distance meters (m).

Time is the actual time taken to cover the distance.

The SI unit of time is seconds (s).

So speed is a derived quantity stating the rate at which change in distance can be observed.

The unit of speed is m/s.

The base quantities used to measure speed are distance and  time.

Explanation:

Speed is defined as the rate of change of distance with time. It is given by the  equation        

SI unit of speed is  

Speed is a scalar quantity that has only magnitude and no direction. The vector equivalent of speed is velocity which is defined as the rate of change of displacement with time.

Since speed is scalar it can only have positive values. But velocity can have negative and positive values.

current flows in a wire

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