Chapter 9, Problem 1SAQ

Which set of wavelengths for light are arranged in order of increasing frequency?

a. 250 nm; 300 nm; 350 nm

b. 350 nm; 300 nm; 250 nm

c. 300 nm; 350 nm; 250 nm

d. 300 nm; 250 nm; 350 nm

Interpretation Introduction

Interpretation: The set of wavelengths for light arranged in the increasing order of frequency is to be identified.

Concept Introduction:

The distance between the two adjacent crests or troughs is called wavelength of light. It is represented by the symbol $\lambda$(lambda).

The inverse of wavelength is called frequency. It is defined as the number of cycles or oscillations that pass through a fixed point in one second.

The wavelength of the light is inversely related to the frequency.

Answer to Problem 1SAQ

Correct answer:

The set wavelengths for light in increasing order of frequency can be arranged as follows:

$350\text{nm};300nm;250nm$. Therefore, option (b) is correct.

Explanation of Solution

Reason for correct option:

The frequency and wavelength of light are inversely related. This can be represented as follows:

$\lambda \alpha \frac{1}{v}$

Here, $\lambda$ is the wavelength of light and $v$ is the frequency.

This implies that the shorter wavelength will have a higher frequency and longer wavelength will have a lower frequency.

Thus, the decreasing order of wavelengths of light represents the increasing order of frequency for the light. The order for the lights with respect to frequency is the reverse of the order for lights with respect to wavelengths. Hence, the correct set of wavelengths for the light representing the increasing order of frequency is $350\text{nm};300nm;250nm.$

Hence, option (b) is correct.

Reasons for incorrect options:

Option (a) is incorrect because according to the above explanation, the set of wavelengths $250nm;300nm;350\text{nm}$ are arranged in decreasing order of frequency. So, it is a wrong answer.

Option (c) is incorrect because according to the above explanation, the set of wavelengths $300nm;350\text{nm};250nm$ are not arranged in increasing order of frequency. So, it is a wrong answer.

Option (d) is incorrect because according to the explanation, the set of wavelengths $300nm;250nm;350\text{nm}$ are not arranged in increasing order of frequency. So, it is a wrong answer.

Hence, options (a), (c), and (d) are incorrect.