G Railroad tracks are made from segments L = 79 m long at T = 20° C. When the tracks are laid, the engineers leave gaps of width l between adjacent segments to allow for thermal expansion. The coefficient of linear expansion is α = 12 × 10-6 °C-1 and engineers design the tracks to withstand temperatures of Tc = 39.5 degrees. (a) Enter an expression, in terms of given variables, for the minimum gap distance l the engineers must leave for a track rated at temperature Tc

Explanation:

L = Initial length of segment = 79 m

T = Normal temperature =

l = Width to be left for expansion

= Coefficient of linear expansion of the material =

= Maximum temperature =

= Change in temperature =

The expression of linear expansion is given by

The expression for the minimum gap distance l the engineers must leave for a track rated at temperature is

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

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