Asubstance of unknown mass absorbs 138 kilojoules of energy, going from 298 to 303 kelvin. if the specific heat of the substance is 7.11 j/g·°c, how much of the substance was present? 3.88 kg 32.3 g 3.88 g 32.3 kg

Heat absorbed to raise the temperature is given by

here

m = mass

c = 7.11 J/g C

Q = 138 KJ

Now by using the above formula we will have

So the amount of the substance will be 3.88 kg

when heated, the valance electrons increased their speed and transferred the heat from electron to electron.   i just took the test.

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