Description : Magnetic tape is made of what three basic materials?
Last Answer : a. Base material. b. Coating of magnetic oxide particles. c. Glue that bonds the particles to the base.
Description : What are the two most common semiconductor materials used in electronic and electro-optic devices?
Last Answer : Silicon and gallium arsenide.
Description : List the types of materials used in fabricating low-loss, long wavelength optical fibers.
Last Answer : Heavy-metal fluorides, chalcogenide glasses, and crystalline materials.
Description : What are the four most common materials used in semiconductor detector fabrication?
Last Answer : Silicon, gallium arsenide, germanium, and indium phosphide.
Description : What combination of materials is used to patch or build up damaged areas of boards?
Last Answer : Epoxy and fiberglass powder.
Description : What characteristics do all ferromagnetic materials have in common?
Last Answer : The relative ease with which they are magnetized
Description : Besides tungsten, what other materials are used for cathodes in vacu
Last Answer : Thoriated-tungsten and oxide-coated metals.
Description : What materials are commonly used as cushions between cable insulation and metallic armor?
Last Answer : Jute and Asphalt coverings.
Description : State two fundamental properties of insulating materials.
Last Answer : Insulation resistance and dielectric strength.
Description : What are three types of nonmetallic insulating materials that can be used in a high-temperature environments?
Last Answer : FEP, extruded polytetrafluoroethylene, and silicone rubber.
Description : . What primary condition must magnetic lines of force meet in order to exist?
Last Answer : Magnetic lines of force must form a continuous closed loop.
Description : When the magnetic field of the inductor is completely collapsed, where is the energy of the tank circuit stored?
Last Answer : . Capacitor.
Description : List two common usages of magnetic amplifiers
Last Answer : Servosystems, temperature recorders, or power supplies
Description : What is used to bias a magnetic amplifier so that the control winding remains free to accept control (input) signals?
Last Answer : A bias winding and associated circuitry.
Description : What is the purpose of the rectifier in a magnetic amplifier?
Last Answer : The rectifier eliminates hysteresis loss.
Description : At what portion of the magnetization curve should a magnetic amplifier be operated?
Last Answer : . The knee of the curve.
Description : What is the basic principle of a magnetic amplifier?
Last Answer : change in inductance in a series LR circuit causes a change in true power.
Description : What is the frequency classification of a magnetic amplifier
Last Answer : An audio (or low) frequency power amplifier.
Description : What the three basic components make up the typical magnetic amplifier?
Last Answer : Two saturable reactors and a transformer.
Description : What two basic types of magnetic devices are used as error detectors?
Last Answer : E-transformer and control transformers.
Description : What is the effect on magnetron operation if the magnetic field strength is too high?
Last Answer : The magnetron will not oscillate.
Description : What can exposure to a magnetic field do to the data on a disk?
Last Answer : Destroy some or all of it.
Description : How should a delicate instrument be protected from a magnetic field?
Last Answer : By shielding or surrounding the instrument with a soft iron case, called a magnetic shield or screen.
Description : In what way do magnetic lines of force differ from electrostatic lines of force?
Last Answer : Electrostatic lines of force do not form closed loops
Description : What is a magnetic line of force?
Last Answer : An imaginary line used to illustrate magnetic effects.
Description : Using Weber’s molecular theory of magnetism, describe the polarity of the magnetic poles produced by stroking a magnetic material from right to left with the south pole of a magnet.
Last Answer : South pole at the right, north pole at the left.
Description : How does the law of magnetic poles relate to the law of electric charges?
Last Answer : They are very similar; like charges repel, unlike charges attract, like poles repel —unlike poles attract.
Description : What type of magnetic material should be used to make a temporary magnet?
Last Answer : A material that exhibits low reluctance and high permeability, such as iron or soft steel.
Description : What equipment should you use to de-magnetize a magnetic tape transport?
Last Answer : A hand-held degausser.
Description : Sometimes it's necessary, but why should you avoid using cotton swabs when cleaning a magnetic tape transport?
Last Answer : Cotton swabs are not lint free.
Description : . How do tape transports with differential velocity capstans maintain a constant tape tension in the area around the magnetic heads?
Last Answer : The supply capstan is slightly larger than the take-up capstan. This causes the take-up capstan to pull the tape slightly faster than the supply capstan feeds the tape.
Description : What are the four basic parts of a magnetic tape recorder's tape transport system?
Last Answer : a. Tape reeling system. b. Tape speed control system. c. Electronic subsystem. d. Basic enclosure.
Description : Why is it important to minimize TBE jitter in magnetic tape recordings where precise timing relationships exist between two or more signals?
Last Answer : The jitter could cause noise and a loss of accuracy.
Description : What number harmonic is the primary harmonic distortion in magnetic tape recorders?
Last Answer : Third-order harmonic.
Description : List four factors that can degrade the frequency response of magnetic tape recorders.
Last Answer : a. A too-high or too-low bias signal level setting for the record head. b. An improper reproduce head gap. c. An improper tape transport speed. d. Poor tape-to-head contact.
Description : What two types of record and reproduce electronics are used by magnetic tape recorders?
Last Answer : . a. Direct record (AM). b. Frequency modulation (FM).
Description : How often should you demagnetize a recorder's magnetic heads?
Last Answer : Every 8 to 25 hours depending on the manufacturer's recommendations.
Description : What type of equipment should you use to demagnetize your recorder's magnetic heads?
Last Answer : A hand-held degausser like the manual degaussers used for degaussing magnetic tape.
Description : What are four sources that can cause magnetic heads to become magnetized?
Last Answer : a. During ac power losses. b. During testing. c. Because of stray magnetic fields. d. From normal use.
Description : How should you clean your recorder's magnetic heads?
Last Answer : With a cotton-tipped applicator soaked in either isopropyl alcohol or a head cleaner recommended by the recorder's manufacturer.
Description : What two preventive maintenance actions must you do regularly to increase magnetic head life and to ensure good tape recording and playback?
Last Answer : a. Keep the heads clean. b. Keep the heads demagnetized.
Description : The way a magnetic head will be used determines how it is constructed. Name three factors that determine the final construction of a magnetic head.
Last Answer : a. Type of head (record, reproduce, or erase). b. Frequencies it will record or reproduce. c. Whether it will be used on a single or multitrack recorder.
Description : Magnetic tape recorders can have up to three different heads installed. What are the three functions performed by a recorder's heads?
Last Answer : Record, reproduce, and erase.
Description : What is the correct way to hold a magnetic tape reel?
Last Answer : Always hold reel by the hub, never by the flanges. Never touch the working tape surface.
Description : When magnetic tapes are ruined, what three factors are normally the cause?
Last Answer : Poor handling, improper storage, or shipping damage.
Description : What method for erasing magnetic tape is much more effective and reliable than using a recorder’s erase head?
Last Answer : Using a magnetic tape degausser
Description : What are two disadvantages of using a recorder’s erase head to erase data recorded on a magnetic tape?
Last Answer : Using an erase head is slow, and it may not completely erase the tape.
Description : You notice steps in the tape pack such as those in figure 2-3. What causes this and how does it damage the magnetic tape?
Last Answer : Pack slip. It's caused by loosely wound tape on a reel that is exposed to excessive vibration or heat. The vibration or heat causes the tape to shift, causing steps in the tape pack. The uneven tape will then rub against the reel's sides and the recorder's tape guides.
Description : When the relative humidity is below 10%, what happens to magnetic tape and parts of a tape recorder that could cause environmental damage?
Last Answer : Dirt build-up caused by static electricity.