Chapter 15, Problem 6STP

To determine

To Choose:The correct option.

Answer to Problem 6STP

The answer is B- $\text{258 Hz or 266 Hz}$ .

Explanation of Solution

Given data:

Number of beats heard is $20$ .

Time in which the beats are heard is $5.0\text{ s}$ .

Frequency of the first note is $f=262\text{ Hz}$ .

Calculation:

Find out the beats per second.

  $\begin{array}{l}\text{Beats per seconds}\\ =\frac{\text{number of beats heard}}{\text{time taken}}\\ =\frac{20}{5}\\ =\text{4 beats}\end{array}$

The two possible frequencies of the second note will be either more than the frequency of the first note or less than it.

Therefore, you have to both add and subtract the frequency of the first note to and from the beats per second, respectively.

  $\begin{array}{l}\text{262}+\text{4}=\text{266 Hz }\\ \text{262}-4=258\text{ Hz}\end{array}$

Conclusion:

Hence the answer is B- $\text{258 Hz or 266 Hz}$ .