If sounds produced by the human vocal cords are approximated as waves on a string fixed at both ends, and the average length of a vocal cord is 15 mm, what is the fundamental frequency of the sound? (note: use 3 m/s for the speed of sound through the vocal cord.)

The fundamental frequency of the sound is: 100 Hertz

Explanation:

We need to remember that the period (T) which unit is the seconds, is the inverse of the frequency (f), which unit is the Hertz, and we call wavelength (λ) to space which the sound is traveling, which unit is the meter. So that the equation which related those variables is: λ = v x T = v / f

where v is the speed of the sound, but the wavelength of the fundamental modo for a string fixed at both ends is: λn=2*L/n; in this case n=1 (fundamental mode) so λ1=(2*0,015)/1 = 0.030 (m). Replaced the values give us for the exercise, we get: λ= 0.030 (m), v = 3 (m/s) so that f = v / λ = 3 (m/s) / 0.030 (m) so the answer is λ = 100 Hertz.

a solenoid is created by wrapping a l = 90 m long wire around a hollow tube of diameter d = 4.5 cm.   the wire diameter is d = 0.9 mm.   the solenoid wire is then connected to a power supply so that a current of i = 9 a flows through the wire.

randomized variablesl = 90 m

d = 4.5 cm

d = 0.9 mm

i = 9 a                                          

write an expression for the number of turns, n, in the solenoid. you do not need to take into account the diameter of the wire in this calculation.

calculate the number of turns, n, in the solenoid.

write an expression for the length of the solenoid (l2) in terms of the diameter of the hollow tube d.

calculate the length of the solenoid (l2)   in meters.

calculate the magnitude of the magnetic field at the center of the solenoid in teslas.

explanation: