21) Sound travels fastest in
a) water
b) vacuum
c) air
d) iron
22) The device used to record the sound is
a) a phonograph
b) an amplifier
c) a headphone
d) a microphone
23) In a vibrating tuning fork of given frequency the amplitude of vibration
a) increases
b) remains the same
c) diminishes
24) One can be recognized by one’s voice along due to the voice’s factor of
a) pitch
b) quality
c) loudness
d) amplitude
25) The characteristics of a musical notes are
a) pitch
b) quality or timbre
c) loudness
d) all the above
26) Apart from iron, another common element which is attracted strongly by a magnet is
a) nickel
b) brass
c) glass
d) copper
27) Sound waves in air travel faster if the
a) pitch is smaller
b) air is warmer
c) frequency is higher
d) wavelength is smaller
28) The electrodes of an electric are lamp are made of
a) copper
b) silver
c) graphite
d) tungsten
29) How long will it take to charge a 10 amp. Hours accumulator at 2 amp. Rate?
a) 5 minutes
b) 2 hours
c) 10 hours
d) 5 hours
30) Air pressure is usually highest when the air is
a) cool and dry
b) cool and moist
c) warm and moist
d) warm and dry