Chapter 5, Problem 74A

Interpretation Introduction

Interpretation:

The reason due to which it is not possible to notice the wavelength of moving objects such as automobiles needs to be explained.

Concept introduction:

Wavelength is directly proportional to velocity of object.

Answer to Problem 74A

The wavelength of automobiles is very small it is not in visible light range so it is impossible to notice it with our naked eye.

Explanation of Solution

Given information:

the wavelength of automobiles is not visible.

Anything that has mass has an associated wavelength.

Wavelength = $\frac{h}{mv}$

Where,

$h$ = Planck’s constant and its value is $6.626176\times {10}^{-34} joule-seconds$$$

$m$ = mass

$v$ = velocity

Visible light range = $3.90\times {10}^{-7}$ to $7.50\times {10}^{-7}$ meters.

For an automobile wavelength

Suppose there is a car with mass 100 kg moving with the speed of 100 m/s.

Now, putting the values in wavelength equation = $\frac{h}{mv}$ = $\frac{6.626176\times {10}^{-34}}{{10}^5\times {10}^2}$ = $6.626176\times {10}^{-41}m$

The above example clearly shows that the wavelength of automobiles is very small and outside of our vision capability so it is not possible to notice it.

Conclusion

The wavelength of automobiles is very small