Question

question 16 of 25 which of the following is an effect of increasing the wavelength of an electromagnetic wave? a. speed decreases. b. speed increases. c. energy increases. d. energy decreases.

Explanation:

Step1: Recall the relationship between speed, wavelength and frequency

The speed $c$ of an electromagnetic wave in vacuum is given by $c = \lambda
u$, where $\lambda$ is the wavelength and $
u$ is the frequency. In a given medium, the speed of electromagnetic - waves is constant (for a non - dispersive medium). So, changing the wavelength does not change the speed.

Step2: Recall the energy - wavelength relationship

The energy of a photon of an electromagnetic wave is given by $E=h
u$, and since $
u=\frac{c}{\lambda}$, we can rewrite the energy formula as $E = \frac{hc}{\lambda}$, where $h$ is Planck's constant and $c$ is the speed of light.
From $E=\frac{hc}{\lambda}$, we can see that energy $E$ is inversely proportional to the wavelength $\lambda$. When $\lambda$ increases, $E$ decreases.

Answer:

D. Energy decreases.