TOEFL Listening: ETS-TOEFL听力机经 - 3P3MG533BXVN72M8P$

What point does the professor make about the magnetic field in electromagnetic radiation? A. Its importance for research will grow in the future. B. It is not always present in visible light C. It is essential to analyze the magnetic component of radiation before analyzing the electric component D. Its strength can be calculated on the basis of the strength of the electric field.