Chapter 7, Problem 7.64P

(a)

Interpretation Introduction

Interpretation:

The total number of photons of red light needed for the optic nerve to trigger a series of impulses that eventually reaches the brain 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:

$E=h\nu$

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:

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

The equation to calculate the energy of a photon is,

$E=h\frac{c}{\lambda }$ (1)

Here,

$c$ is the speed of light.

$\lambda$ is the wavelength.

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

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

(b)

Interpretation Introduction

Interpretation:

The total number of photons of blue light needed for the optic nerve to trigger a series of impulses that eventually reaches the brain 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:

$E=h\nu$

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:

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

The equation to calculate the energy of a photon is,

$E=h\frac{c}{\lambda }$ (1)

Here,

$c$ is the speed of light.

$\lambda$ is the wavelength.

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

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