1.
Which of the following devices would most likely be used for adjusting the frequency settingof a digital radio transmitter or receiver?
Correct Answer
C. An optical shaft encoder
Explanation
An optical shaft encoder would most likely be used for adjusting the frequency setting of a digital radio transmitter or receiver. This device is designed to convert the position or motion of a shaft into an analog or digital signal. By rotating the shaft, the optical encoder can provide precise and accurate feedback on the position or rotation angle, which can be used to adjust the frequency setting of the transmitter or receiver.
2.
Collimation of IR rays can be done by means of
Correct Answer
A. An ordinary lens.
Explanation
An ordinary lens can be used to collimate IR rays, which means to make them parallel. This is because a lens can refract the rays in such a way that they all converge at a single point, creating parallel rays. A selsyn is a type of electric motor and a log polar transform system is a mathematical technique used in image processing, so they are not suitable for collimating IR rays. Therefore, the correct answer is an ordinary lens.
3.
A computer map
Correct Answer
A. Can help a robot find its way around.
Explanation
A computer map can help a robot find its way around by providing a visual representation of the robot's surroundings and the paths it can take. The map can be created using various sensors and algorithms that allow the robot to navigate and make decisions based on the map's information. This enables the robot to plan its movements and avoid obstacles, ultimately helping it navigate its environment effectively.
4.
The distance of a target from a radar station is called
Correct Answer
C. The range.
Explanation
The distance of a target from a radar station is referred to as the range. Range is a fundamental concept in radar systems, representing the distance between the radar station and the target being detected. It is an essential parameter in radar measurements and plays a crucial role in determining the position and location of the target. The other options, such as resolution, azimuth, and transform, do not specifically represent the distance of a target from a radar station.
5.
Which of the following devices is best for use as an ultrasonic pickup?
Correct Answer
B. A piezoelectric transducer
Explanation
A piezoelectric transducer is the best device for use as an ultrasonic pickup because it is specifically designed to convert mechanical vibrations into electrical signals. Ultrasonic waves are mechanical vibrations at a frequency higher than the human hearing range, and a piezoelectric transducer can effectively detect and convert these vibrations into electrical signals. The other options listed, such as a back-pressure transducer, elastomer pressure transducer, and capacitive pressure transducer, are not specifically designed for ultrasonic pickup and may not be as sensitive or accurate in detecting ultrasonic waves.
6.
What do loran and the GPS have in common?
Correct Answer
D. They both involve measurement of distances to determine the location of a receiver.
Explanation
Both loran and GPS systems involve measuring distances to determine the location of a receiver. Loran uses the time difference of arrival (TDOA) of radio signals from multiple transmitters to calculate the position, while GPS uses trilateration based on the time it takes for signals to travel from satellites to the receiver. In both cases, distance measurements are crucial in determining the receiver's location.
7.
A bright spot close to, and directly to the left of, the center of a conventional radar displayindicates the presence of a target
Correct Answer
B. At close range, west of the observing station.
Explanation
A bright spot close to, and directly to the left of, the center of a conventional radar display indicates the presence of a target at close range, west of the observing station. This is because the radar display typically represents the area around the observing station, with the center of the display representing the station itself. Therefore, a bright spot to the left of the center indicates a target that is to the west of the station. Additionally, the fact that the spot is close to the center suggests that the target is at a close range.
8.
Which of the following systems enables a vessel to navigate entirely from its own frame ofreference, without the need for any electronic devices external to itself?
Correct Answer
A. An epipolar navigation system
Explanation
An epipolar navigation system enables a vessel to navigate entirely from its own frame of reference, without the need for any external electronic devices. This system uses the concept of epipolar geometry, which involves the use of multiple cameras and triangulation to determine the position and orientation of the vessel. By relying solely on its internal sensors and cameras, the epipolar navigation system can accurately navigate without the need for GPS or other external devices.
9.
Ultrasonic waves travel through a vacuum
Correct Answer
D. Forget it! No form of acoustic wave can travel through a vacuum.
10.
Which of the following devices or techniques makes use of artificially generated magneticfields to facilitate location within a work environment?
Correct Answer
D. None of the above
Explanation
None of the devices or techniques mentioned in the options make use of artificially generated magnetic fields to facilitate location within a work environment. A dynamic transducer is a device used to convert energy from one form to another, such as converting electrical energy into mechanical motion. Epipolar navigation is a technique used in computer vision to estimate the motion of a camera. Capacitive proximity sensing is a technique used to detect the presence or absence of an object without physical contact. Therefore, none of these options are relevant to the use of artificially generated magnetic fields for location within a work environment.
11.
Which of the following is not an example of a transducer?
Correct Answer
D. All of the above are examples of transducers.
Explanation
All of the options given in the question, namely a microphone, a radio antenna, and a headset, are examples of transducers. A transducer is a device that converts one form of energy into another. In the case of a microphone, it converts sound energy into electrical signals. A radio antenna converts electromagnetic waves into electrical signals, and a headset converts electrical signals into sound energy. Therefore, all the options listed are examples of transducers.
12.
A foam-like material, having a resistance that varies depending on how much it iscompressed, is known as
Correct Answer
A. An elastomer.
Explanation
An elastomer is a foam-like material that has the property of varying resistance when compressed. This means that when pressure is applied to the elastomer, its resistance changes. This characteristic makes it useful in various applications such as pressure sensors, touch screens, and vibration dampeners. A fluxgate magnetometer is a device used to measure magnetic fields, and a piezoelectric substance generates an electric charge when subjected to mechanical stress. Neither of these options accurately describes a foam-like material with variable resistance when compressed, making the correct answer "an elastomer."
13.
A stepper motor
Correct Answer
B. Resists applied torque when stopped with current going through its coils.
Explanation
A stepper motor resists applied torque when stopped with current going through its coils. This means that when the motor is not moving, it requires a certain amount of force to overcome the resistance created by the current flowing through its coils. This characteristic allows the motor to hold its position when not in motion, making it suitable for applications that require precise positioning and holding capabilities.
14.
A permanent magnet is a key component of
Correct Answer
C. A dynamic micropHone.
Explanation
A permanent magnet is a key component of a dynamic microphone because it is used to generate the magnetic field that interacts with the diaphragm. When sound waves hit the diaphragm, it vibrates and causes changes in the magnetic field, which in turn generates an electrical signal. This signal is then amplified and converted into sound. Therefore, the permanent magnet is essential for the functioning of a dynamic microphone.
15.
An electric motor is an example of
Correct Answer
A. An electromechanical transducer.
Explanation
An electric motor is considered an electromechanical transducer because it converts electrical energy into mechanical energy. It uses the principle of electromagnetic induction to create a rotating magnetic field, which in turn produces mechanical motion. This conversion of energy from one form to another is characteristic of an electromechanical transducer.
16.
A capacitive proximity sensor should not be expected to detect the presence of
Correct Answer
D. A steel post.
Explanation
A capacitive proximity sensor works by detecting changes in an electrical field. It is designed to detect objects that have a higher dielectric constant, such as metal or human bodies. A wooden chair, a metal desk, and a large dog may not have a high enough dielectric constant to be detected by the sensor. However, a steel post, being made of metal, would have a higher dielectric constant and would be detected by the sensor.
17.
A well-designed photoelectric proximity sensor
Correct Answer
D. Is not easily fooled by stray sources of light.
Explanation
A well-designed photoelectric proximity sensor is not easily fooled by stray sources of light because it is designed to specifically detect and respond to changes in light intensity caused by the presence or absence of objects. It is able to distinguish between the intended target and any other sources of light that may be present in the environment, ensuring accurate and reliable detection.
18.
An acoustic transducer can translate an ac electrical signal into
Correct Answer
B. Sound or ultrasound.
Explanation
An acoustic transducer is a device that converts one form of energy into another in the form of sound or ultrasound. It is designed to convert an electrical signal into sound waves or ultrasound waves, making it capable of producing audible or inaudible sound depending on the frequency. This explanation aligns with the answer choice "sound or ultrasound."
19.
Body capacitance can be a problem with
Correct Answer
C. Capacitive pressure sensors.
Explanation
Body capacitance refers to the electrical charge that can be stored by a person's body. This can interfere with the performance of electrostatic transducers and elastomer pressure sensors, as the charge can be transferred to the sensor and affect its accuracy. However, capacitive pressure sensors are specifically designed to measure changes in capacitance, so they are less affected by body capacitance and are therefore not as problematic in this regard. Therefore, the correct answer is capacitive pressure sensors.
20.
Which of the following devices can be used to limit the torque or force applied by anelectromechanical device such as a robot?
Correct Answer
A. A back-pressure sensor
Explanation
A back-pressure sensor can be used to limit the torque or force applied by an electromechanical device such as a robot. This sensor measures the pressure created by the device and can send signals to control systems to adjust the force or torque accordingly. By monitoring and regulating the back-pressure, the sensor ensures that the device does not exert excessive force or torque, preventing damage to the device or the objects it interacts with.