Guided Practice
Learn
In this guided practice lesson, you will apply what you learned about waves, light, and sound through structured exercises. We will work through problems together, building your confidence before independent practice.
Key Concepts Review
- Waves transfer energy from one place to another without transferring matter.
- Amplitude measures the height of a wave from rest to crest.
- Wavelength is the distance between two identical points on consecutive waves.
- Frequency describes how many waves pass a point in one second.
- Light waves can travel through empty space (vacuum).
- Sound waves need a medium (solid, liquid, or gas) to travel.
Practice Strategy
When solving wave problems:
- Read the problem carefully and identify what is being asked.
- Draw a diagram if it helps visualize the wave.
- Identify known information (amplitude, wavelength, frequency).
- Apply your knowledge to find the answer.
- Check if your answer makes sense.
Examples
Example 1: Identifying Wave Parts
Problem: A wave has a height of 3 meters from its resting position to its highest point. What is this measurement called?
Solution: The height from the resting position to the highest point (crest) is called the amplitude. So the amplitude of this wave is 3 meters.
Example 2: Comparing Light and Sound
Problem: During a thunderstorm, you see lightning before you hear thunder. Why does this happen?
Solution: Light travels much faster than sound. Light travels at about 300,000 kilometers per second, while sound travels at about 343 meters per second in air. This is why we see the lightning flash before we hear the thunder.
Example 3: Wave Medium
Problem: Can astronauts in space hear each other talk without a radio? Explain why or why not.
Solution: No, astronauts cannot hear each other in space without a radio. Sound waves require a medium (like air) to travel through. Space is a vacuum with no air, so sound cannot travel through it. They must use radios that transmit information using light waves (radio waves), which can travel through space.
Practice
Now try these problems on your own. Click each question to reveal the answer after you have attempted it.
Question 1: What type of wave requires a medium to travel through?
Answer: Sound waves require a medium (solid, liquid, or gas) to travel through. They cannot travel through empty space.
Question 2: If you increase the amplitude of a sound wave, what happens to the sound?
Answer: The sound becomes louder. Greater amplitude means more energy in the wave, which we perceive as increased volume.
Question 3: Which travels faster: light or sound? Give an example from everyday life that proves this.
Answer: Light travels faster than sound. Examples include: seeing lightning before hearing thunder, seeing a distant firework explode before hearing the boom, or seeing someone far away clap before hearing the sound.
Question 4: What happens to light when it hits a mirror?
Answer: Light reflects off the mirror. The light bounces back at the same angle it arrived, which is why we can see our reflection.
Question 5: A wave has 10 complete cycles passing a point in 5 seconds. What is the frequency of this wave?
Answer: The frequency is 2 waves per second (or 2 Hz). Frequency = number of waves divided by time = 10 waves / 5 seconds = 2 waves per second.
Question 6: Why do sounds seem muffled when you are underwater?
Answer: Sound travels differently through water than through air. Our ears are designed to hear sounds in air. While sound actually travels faster in water, the way our ears receive and process the vibrations changes underwater, making sounds seem muffled or distorted.
Question 7: What is the distance from one wave crest to the next wave crest called?
Answer: This distance is called the wavelength. It can be measured from any point on a wave to the same point on the next wave.
Question 8: How does a drum make sound?
Answer: When you hit a drum, the drum head vibrates. These vibrations push and pull on the air molecules around it, creating sound waves that travel through the air to your ears.
Question 9: What happens to sound when the frequency of a wave increases?
Answer: When frequency increases, the pitch of the sound becomes higher. High-frequency sounds are high-pitched (like a whistle), and low-frequency sounds are low-pitched (like a bass drum).
Question 10: Can light travel through solid objects? Explain your answer.
Answer: It depends on the material. Light cannot travel through opaque objects (like wood or metal). Light can travel through transparent objects (like glass or clear water). Some materials are translucent, meaning they let some light through but scatter it (like frosted glass).
Check Your Understanding
After completing the practice problems above, review these key takeaways:
- Sound waves need a medium; light waves do not.
- Amplitude affects loudness (sound) and brightness (light).
- Frequency affects pitch (sound) and color (light).
- Wavelength is the distance between identical points on consecutive waves.
- Light travels much faster than sound.
Next Steps
- Review any concepts that felt challenging
- Move on to the next lesson when ready
- Return to practice problems periodically for review