Electromagnetic energy, as we know it, is present from high energy/ frequency gamma waves to long wavelength AM radio frequencies. We can sense a narrow frequency range from it in terms of heat or visible light. Electromagnetic interference (EMI) or radio frequency interference (RFI) shielding refers to shielding of electrical and electronic devices, or living organism, from unwanted electromagnetic disturbance. How EMI and RFI Shielding Works Nature of electromagnetic energy