Television sets (particularly older models) produce a ``whistle\'\' sound at abo

Question

Television sets (particularly older models) produce a ``whistle'' sound at about 15.8 kHz (this is the frequency that the electron beam sweeps across the face of the screen). This sound is audible to most youngsters and adults who haven't lost their high-frequency hearing. Imagine that a TV set is on (with the ``mute'' on) in your sister's bedroom as you walk by in the hallway. If your sister's door is ajar, leaving an opening 10 cm wide, and your ear is about 1 m from the door as you walk by, for about how many centimeters of your walk will you be able to hear the TV ``whistle'' (if you can at all)?

Explanation / Answer

wavelength of the sound waves,?= speed of sound / frequency of sound waves

= 343 / (15.8 * 1000)

= 0.217 m

= 2.17 cm

to hear the whistle, the ears should be at a distance of 2*L*? / d

= 2 * 100cm * 2.17cm / 10cm

= 43.4 cm

So, 43.4 cm of my walk make me able to hear the TV whistle.

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.