An open vertical tube has water in it. A tuning fork vibrates over its mouth. As the water level is lowered in the tube, the seventh foss (zef86) – Homework 10, oscillations and waves 19-20 – dowd – (PriceEPHY11920 2) 5 resonance is heard when the water level is 55.25 cm below the top of the tube. 55.25 cm What is the wavelength of the sound wave? The speed of sound in air is 343 m/s. Answer in units of cm

Wavelength = 17cm

Frequency = 2017.65 s^(-1)

Explanation:

A) Standing wave is the result of superposition of two identical waves with only the difference being that they travel in opposite directions to each other.

Now, quarter wavelength transmission line, the number of quarter wavelengths in the length of the pipe is given as;

J = 2N - 1

Where N is the number of nodes in the air column.

Question says the 7th resonance is heard at that water level, thus, N = 7

So, J = 2(7) - 1 = 14 - 1 = 13

Now, J is also expressed as, L/(λ/4)

Where L is the water level and λ is the wavelength.

From the question, L = 55.25 cm

Thus, L/(λ/4) = 13

Let's make λ the subject ;

λ = 4L/13

λ = (4 x 55.25)/13

λ = 221/13

λ = 17cm

Now, frequency is found from the formula ;

f = V/λ

From the question, v = 343 m/s

λ = 17cm = 0.17m

Frequency = 343/0.17 = 2017.65 s^(-1)

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the answer is the first electromagnet (a). this is because it has more coils around the ferromagnetic material. increasing the number of coils increases the surface area in which the metal interacts with the current in the coil. this enables more atoms in the metal to become aligned hence becoming more magnetized.