former is half of the current in the primary of Question 17 the transformer. part 1 of 1 10 points 4. The current in the secondary of the trans- The electric field in an electromagnetic former is the same as the current in the pri- wave (in vacuum) is described by mary of the transformer. E = Emas sin(kx - wt), Question 15 where Emar = 56 N/C and k = 9 x 10 m-1 part 1 of 1 10 points The speed of light is 2.99792 x 10" m/s. Find the amplitude of the corresponding Can an officiert transformer step up en magnetic wave. ergy? Answer in units of T. 1. No, there is no such thing as an "efficient Question 18 transformer". part 1 of 1 10 points 2. No, energy is conserved and cannot be What is the principal difference between a stepped up. radio wave and visible light? 3. Theoretically yes, but it is hard to build 1. Radio waves are sound waves. such transformers in practice. 2. Light is more powerful than radio waves. 4. It cannot be determined. 3. Radio waves are not electromagnetic 5. Yes, stepping up voltage is the same as waves. stepping up energy. 4. They travel at different speeds. 6. Yes, provided that the transformer is made of special material such as amino acid 5. Radio waves have lower frequencies than or other organic compounds, visible light waves. Question 16 Question 19 part 1 of 1 10 points part 1 of 1 10 points Which of the folowing has the highest fre- What is the relationship between the fre- quency? quency of light and its color? 1. ultraviolet light 1. There is no relationship between the fre- quency of light and its color. 2. visible light 2. Lights of different frequencies are per- 3. X ray ceived as different colors. 4. infrared light 3. The lowest-frequency light we detect ap- pears to most people as the color violet. 5. radio wave 4. None of the other choices is right. 6. gamma ray 5. The highest-frequency light we detect ap- pears to most people as the color red