Question

question 6 (1 point)
(02.04 lc)
which form of electromagnetic radiation is given off by the sun and is why people are encouraged to use sunscreen?

○ a gamma ray
○ b microwave
○ c radio wave
○ d ultraviolet

question 7 (1 point)
(02.04 mc)
the table compares the wavelength of some unknown electromagnetic waves:

comparison of wavelength
electromagnetic wave | wavelength
a | 10⁻⁴ m
b | 10⁻⁶ m
c | 10² m
d | 10⁰ m

which electromagnetic wave has the highest frequency?

○ a wave a
○ b wave b
○ c wave c
○ d wave d

Explanation:

Question 6

Sunscreen is used to protect against ultraviolet (UV) radiation from the sun, which can cause skin damage. Gamma rays, microwaves, and radio waves from the sun are not the primary reason for using sunscreen.

Step1: Recall the relationship between wavelength ($\lambda$) and frequency ($f$)

The speed of light $c$ (for electromagnetic waves) is related to wavelength and frequency by the formula $c = \lambda f$. Since $c$ is constant, frequency $f$ is inversely proportional to wavelength $\lambda$ (i.e., $f=\frac{c}{\lambda}$). So, the smaller the wavelength, the higher the frequency.

Step2: Compare the wavelengths of the waves

• Wave A: $\lambda_A = 10^{-4}\,m$
• Wave B: $\lambda_B = 10^{-6}\,m$
• Wave C: $\lambda_C = 10^{2}\,m$
• Wave D: $\lambda_D = 10^{0}\,m = 1\,m$

Among these, $10^{-6}\,m$ (Wave B) is the smallest wavelength.

Answer:

d. Ultraviolet

Question 7