Consider an audio tape recorder in the following questions.
1. Suppose you send a constant current through the coil of a tape recorder's head. As the tape passes by the head describe the magnetization that is recorded on the tape.
2. You want to hear what the signal you recorded in question 1 sounds like so you rewind the tape and press play on the recorder. What do you hear and why?
3. Now suppose that you connect the coil of the recording head across a standard electrical outlet in your house. Describe the current that flows in the coil inside the recorder's head. Be sure to include both the amount (descriptively with words like more, less, large, small…) and the direction in your description.
4. With the current from question 3 running through the recording head, describe the magnetization that is produced in the tape as it travels past the recording head. Be sure to include both the direction and depth of the magnetization in your description.
5. You are using your tape recorder to play a tape with music recorded on it. When you press the pause button, the tape stops moving past the head, but the head continues to send whatever current is produced to the speakers. Why do you hear nothing instead of a continuous tone at the frequency (pitch) of the sound that was playing when you hit pause?
6. Some magnetic tapes use tiny, elongated iron particles, which have only a single magnetic domain. Briefly explain why larger iron particles, which have many magnetic domains, cannot be used to store the information magnetically.
There is a brief description of a video tape recorder at the end of chapter 12.5. In a video tape recorder the head does not remain stationary as the tape moves past. Instead, the head is on a spinning drum that sweeps it diagonally across the tape. Video information is written in diagonal stripes across the tape as it is slowly advanced under the spinning drum.
7. If you are watching a movie using your video recorder and you press the pause button, an image continues to appear in the television screen. Describe what the tape and head are doing while the video recorder is paused.
8. Most video recorders will automatically stop displaying the image if they have been paused for too long. This keeps the recorded from damaging the tape. Explain why leaving the recorder paused for too long will damage the tape by describing the forces between the tape and the head, which are gently pressed against one another.