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21. A radio station broadcast at 30 metre band. The frequency of the carrier wave transmitted by this station is ____.
A. 10 Hz
B. 1000 Hz
C. 10 MHz
D. 100 MHz
ANSWER:C
SOLUTION :10 MHz
22. What measure the response of the ear to the sound?
A. Amplitude
B. Intensity
C. Frequency
D. Loudness
ANSWER:D
SOLUTION:Loudness is the measure of the ear’s response to sound. It’s measured in decibels (dB). While loudness is related to sound intensity, it’s not directly proportional. Even if two sounds have the same intensity, one may sound louder than the other because the ear detects it better.
23. In any medium as we increase the temperature the speed of sound ____.
A. Increases
B. Decreases
C. Remains same
D. None of these
ANSWER:A
SOLUTION:The speed of sound in a medium increases as the temperature increases. This is because molecules at higher temperatures have more energy and vibrate faster, allowing sound waves to travel faster. The speed of sound increases by about 0.61 meters per second for each degree centigrade rise in temperature.
24. Speed of sound in Aluminum is ____.
A. Zero
B. 344 m/s
C. 6420 m/s
D. None of these
ANSWER:C
SOLUTION:The speed of sound in Aluminium at 25 deg Celsius is around 6420 m/s. The matter or substance through which sound is transmitted is called a medium. It can be solid, liquid, or gas.
25. Name the medical instrument used for listening to sounds produced within the body, chiefly in the heart or lungs.
A. SONAR
B. Ultrasound
C. Stethoscope
D. None of these
ANSWER:C
SOLUTION:The medical instrument used to listen to sounds produced within the body, chiefly in the heart or lungs, is a stethoscope. It’s used in a technique called auscultation.
26. The audible range of sound for human beings extends from about ____.
A. 2000 Hz to 20000 Hz
B. 200 Hz to 20000 Hz
C. 20 Hz to 20000 Hz
D. None of these
ANSWER:C
SOLUTION :The audible range of sound for humans is 20–20,000 Hz, which is the range of frequencies that humans can hear. Frequencies above 20,000 Hz are known as ultrasound.
27. Children under the age of five and some animals, such as dogs can hear up to _____.
A. 15 kHz
B. 20 kHz
C. 25 kHz
D. 30 kHz
ANSWER:C
SOLUTION:Audible range of human beings 20 Hz to 20000 Hz. Children under the age of five years and dogs can hear upto 25 kHz.
28. As people grow older their ears become less sensitive to ____ frequencies.
A. Lower
B. Higher
C. Infrasonic
D. None of these
ANSWER:B
SOLUTION: As people grow older, their ears become less sensitive to higher frequencies. This is called presbycusis, which is a common type of age-related hearing loss that affects both ears equally. People with presbycusis may also have trouble distinguishing between certain sounds.
29. Sounds of frequencies below 20 Hz are called ____.
A. Audible range
B. Infrasound
C. Ultrasound
D. None of these
ANSWER:B
SOLUTION: Amplitude Modulation (AM) is preferred for picture transmission on TV because of the following reasons: The distortion which arises due to interference between multiple signals is more in FM than AM because the frequency of the FM signal continuously changes.
30. The _____ produces and transmits ultrasonic waves.
A. Detector
B. Transmitter
C. Receiver
D. None of these
ANSWER:A
SOLUTION: In Analog TV broadcast, Audio signals are transmitted by Frequency Modulation (FM), while video signals are transmitted by Amplitude Modulation (AM).