Multiple Choice

17.

Which type of EM radiation has the shortest wavelengths?

gamma rays
infrared waves
blue light
microwaves

18.

Which form of EM radiation has the most penetrating ability?

red light
microwaves
gamma rays
infrared radiation

19 .

Why are high-frequency gamma rays more dangerous to humans than visible light?

Gamma rays have a lower frequency range than visible light.
Gamma rays have a longer wavelength range than visible light.
Gamma rays have greater energy than visible light for penetrating matter.
Gamma rays have less energy than visible light for penetrating matter.

20 .

A dog would have a hard time stalking and catching a red bird hiding in a field of green grass. Explain this in terms of cone cells and color perception.

Dogs are red-green color-blind because they can see only blue and yellow through two kinds of cone cells present in their eyes.
Dogs are only red color-blind because they can see only blue and yellow through two kinds of cones cells present in their eyes.
Dogs are only green color-blind because they can see only blue and yellow through two kinds of cones cells present in their eyes.
Dogs are color-blind because they have only rods and no cone cells present in their eyes.

21.

To compare the brightness of light bulbs for sale in a store, you should look on the labels to see how they are rated in terms of ____.

frequency
watts
amps
lumens

22.

What is the wavelength of red light with a frequency of 4.00 × 10¹⁴ Hz?

2.50 × 10¹⁴ m
4.00 × 10¹⁵ m
2.50 × 10⁶ m
7.50 × 10^-7 m

23.

What is the distance of one light year in kilometers?

2.59 × 10¹⁰ km
1.58 × 10¹¹ km
2.63 × 10⁹ km
9.46 × 10¹² km

24.

How does the illuminance of light change when the distance from the light source is tripled? Cite the relevant equation and explain how it supports your answer.

$Illuminance = \frac{P}{4 π r^{2}}; Illuminance = \frac{P}{4 π r^{2}};$ if distance is tripled, then the illuminance increases by 19 times.
$Illuminance = \frac{P}{4 π r}; Illuminance = \frac{P}{4 π r};$ if distance is tripled, then the illuminance decreases by 13 times.
$Illuminance = P · 4 π r^{2}; Illuminance = P · 4 π r^{2};$ if distance is tripled, then the illuminance decreases by 9 times.
$Illuminance = P · 4 π r; Illuminance = P · 4 π r;$ if distance tripled, then the illuminance increases by 3 times.

25.

A light bulb has an illuminance of 19.9 lx at a distance of 2 m . What is the luminous flux of the bulb?

500 lm
320 lm
250 lm
1,000 lm