The standard heat of formation of nabr is -360.0 kj mol-1. the energy needed to vaporize one mole of br2(l) to give br2(g) is 31 kj mol-1. energy needed to vaporize one mole of na(s) is 107.8 kj. the first ionization energy of na is 495.4 kj mol-1. the bond energy of br2 is 192 kj per mole of br—br bonds. the lattice energy of nabr is -743.3 kj mol-1.

trig 15.3 cos

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

technology is the application of the knowledge gained by science.