# Heat, Light, and Sound

### Overall Rating

Subject:
Physical Science
Duration:
30 minutes
Setting:
outdoors
National/State Standards:
Utah State Science Core Curriculum Topic Standard Six: Students will understand properties and behavior of heat, light, and sound.
Keywords:
Waves, reflection, refraction, conduction, Convection, absorption, radiation, UV light, birds

### Overview

In the classroom, students review the properties of waves. On the field trip, students investigate what objects absorb and retain the most heat, and then use sound waves to find local birds. They observe how lenses change light waves, discovering how common objects use lenses to bend light to meet our needs, and they investigate how sunscreen blocks UV waves. Back in the classroom, students discuss when our use of heat, light, or sound waves becomes overuse.

### Objective(s)

PRET-TRIP ACTIVITY
What is a Wave?

a. Describe the characteristics of a wave.
b. Name three types of waves.

STATION #1
Whose Got the Heat?

a. Name two characteristics of substances that absorb heat.
b. Describe why water can change the temperature of an object.

STATION #2
The Sounds of Spring

a. Identify at least one wetlands bird.
b. Name two reasons for a bird to sing.

STATION #3
UV or Not UV?

b. name three ways it affects humans
c. list three ways to protect themselves from getting too much UV

STATION #4
Uses of Lenses

a. Explain why humans would want to bend light.
b. Name three objects humans have created out of lenses.
c. Describe how one object with a lens works.

POST-TRIP
Can We Get Too Much?

a. Name four instances where too much heat, light, or sound was harmful to humans.
b. Name two instances where too much heat, light, or sound was harmful to animals.

### Background

Energy is transported around the universe in the form of waves. Sound waves, light waves, ocean waves, heat waves, and radio waves are some examples. The shape of the wave determines its characteristics. The amplitude is the height of the wave. The crest is the top of the wave. The trough is the bottom of the wave. Frequency is the number of times the wave crests in a given period. Wavelength is the distance between two crests. The speed of the wave is determined by multiplying the frequency times its wavelength. If the crest on one wave occurs at the same time and place as a trough in another wave they are considered out of phase. These waves can interfere with each other or even cancel each other out.

Sound travels in waves. Sound is created by the vibrations or the back and forth movement of objects. When an object vibrates, it sends sound waves off in all directions. However, sounds waves can only travel through mediums such as air, water, and objects. In other words, sound cannot travel in a vacuum. Sound waves travel at different speeds trough different mediums. The denser the material, the faster the wave travels. Pitch is the highness or lowness of a sound as we hear it. High-pitched sounds have a high frequency, and low-pitched sounds have a low frequency. Humans and animals communicate, or express their thoughts, by vibrating their vocal cords. Thicker cords vibrate more slowly and have a lower pitch. Similarly, the thicker strings on stringed instruments vibrate more slowly and produce deeper pitched tones. As boys get older, their vocal cords thicken and their voice drops. The intensity or the amplitude of the sound wave determines loudness.

The sun emits electromagnetic radiation in the form of waves. This radiation travels out from the sun in straight lines in all directions. A small portion of this radiation reaches the earth. We see small portions of this radiation as visible light. Television signals, radio waves, X-rays, Ultraviolet rays, microwaves, and infrared radiation have wavelengths that are either too short or too long for us to see. Upon encountering an object, light waves can be refl ected, refracted, or absorbed. When light is reflected, it is bent. The angle at which the light is reflected depends on the shape of the surface it is reflected from and the angle at which the light strikes the surface. Many objects that appear to produce light are only reflecting the light of another object. When light travels through a transparent object, it is bent or refracted. The shape of the object determines how the light is bent. Prisms, and sometimes water drops, bend light so that the different wavelengths are separated. Lenses bend light so that objects appear larger or smaller depending on the shape of the lens. Humans have created many different types of lenses that help us to explore and understand the world around us (Atwater et al, 1993).

Another way we perceive radiant energy is in the form of heat. Heat moves from one object to another by conduction, convection, or radiation. Conduction is the transfer of heat from one substance to another by direct contact. When either fast or slow moving particles touch one another, energy is transferred. Slow moving particles speed up, and fast moving particles slow down. Convection is the circulation of heat within liquids or gasses. Heating substances causes convection. When the particles begin to move faster, they get lighter and rise, allowing space for denser, cooler substances to fall. Radiation is the transfer of heat through open space in the form of waves. All warm objects emit heat waves or radiate (Utah State Offi ce of Education, 2002).

### Extensions

STATION #1
Whose Got the Heat?

In the hot sun, place a wooden bowl, a white plate, an iron pan, a plastic plate, some cotton cloth, and some lettuce leaves. On each of the surfaces, crack open an egg. Check on the eggs every five minutes until one of the eggs has fried.

STATION #2
The Sounds of Spring

Have students record bird songs in the same area for several days in a row. Students should chart how often particular calls were heard on each day. Compare to charts made by other students in other location. Have students hypothesize why different birds were heard at different locations.

STATION #3
UV or Not UV?

Let students make bracelets for themselves using the string and 5 or 6 beads.

STATION #4
Uses of Lenses

Tell students to pretend they are alone on a desert island with only a magnifying glass. Give students one minute to write down all the uses they can for the magnifying glass. Have each student write a short story telling how the use of the magnifying glass saved his or her life.

Atwater, M., Baptiste, P., Daniel, L., Hackett., et al. (1993). Wave energy: Teacher’s planning guide. New York: Macmillan/McGraw-Hill Science.

Hartshorne, C. (1992). Born to sing. Bloomington, ID: Indiana University Press.

Sherwood, E., Williams, R., & Rockwell, R. (1990). More mudpies to magnets. Mt. Rainier, MD: Gryphon House.

Twiest, M. & Twiest, M. (2004) The scoop on sunscreen. Science and Children. V 41. N 9. Summer. pp 40-41.

Utah State Offi ce of Education. (2002). Teacher resource book: Grade six. Salt Lake City: Author.