Which combination of a wire coil and a core would make the weakest electromagnet

Hen a gfci receptacle device is installed on a 20-ampere branch circuit (12 awg copper), what is the minimum volume allowance (in cubic inches) required for conductor fill for each conductor in the outlet box?

Afrequency generator sends a 550 hz sound wave through both water and ice. what is the difference in wavelength between the wave produced in ice and the wave produced in water?

Specific heat refers to the amount of heat required to change 1 gram of a substance by degree(s) celsius