Chapter 7, Problem 7.86P

(a)

Interpretation Introduction

Interpretation:

The colours produced by the emission of radiations by strontium and barium salts at $641\text{ nm}$ and $493\text{ nm}$ are to be determined.

Concept introduction:

Electromagnetic waves are radiations that are formed by oscillating electric and magnetic fields. The electric and magnetic field components of an electromagnetic wave are perpendicular to each other. The general properties of electromagnetic waves are as follows:

1) Electromagnetic waves travel at the speed of light.

2) Electromagnetic waves are transverse in nature.

3) Electromagnetic waves may be polarized.

4) Electromagnetic waves are not deflected by an electric or magnetic field.

5) Electromagnetic waves need no medium for propagation.

(b)

Interpretation Introduction

Interpretation:

The energy of the radiations emitted by strontium and barium salts for $5\text{ g}$ of chloride salts of each is to be determined.

Concept introduction:

Electromagnetic waves are radiations that are formed by oscillating electric and magnetic fields. The electric and magnetic field components of an electromagnetic wave are perpendicular to each other.

Energy is proportional to the frequency and is expressed by the Plank-Einstein equation as follows:

$E=h\nu$ (1)

Here,

$E$ is the energy.

$h$ is the Plank’s constant.

$\nu$ is the frequency.

The equation to relate the frequency and wavelength of electromagnetic radiation is as follows:

$\nu =\frac{c}{\lambda }$

Equation (1) can be modified as,

$E=h\left(\frac{c}{\lambda }\right)$

Here,

$c$ is the speed of light.

$\lambda$ is the wavelength.

The conversion factor to convert wavelength from $\text{nm}$ to $\text{m}$ is,

$1\text{ nm}=1\times {10}^{-9}\text{ m}$