Which one of the following waves is used for detecting forgery in currency notes?
A. Ultraviolet waves
B. Infrared waves
C. Radio waves
D. Microwaves
Answer: Option A
A. Ultraviolet waves
B. Infrared waves
C. Radio waves
D. Microwaves
Answer: Option A
Which of the following substances will have the lowest speed of sound?
A. Water
B. Steel
C. Glasss
D. Air
What is the approximate range of sound for humans?
A. 20Hertz to 2000 Hertz
B. 20Hertz to 200Hertz
C. 20 Hertz to 20000 Hertz
D. 2 Hertz to 2000 Hertz
Loudness of sound depends upon which of the following?
A. Frequency
B. Wavelength
C. Amplitude
D. Overtones
A. On land
B. In air
C. In space
D. Underwater
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