Waves Tutorial - Weebly



WAVE BASICS

Online Lab 40 pts Name:

1. Open the simulator at PhET Simulations ( Play With Sims ( Sound and Waves ( Wave on a String.

2. Let’s start by playing around with the simulator. Set the damping to 10 and give the wrench an upward jerk and observe the wave pulse that is created and reflected. Record below what you observe (2 pts):

3. Now remove the damping (set to 0) and try again. How did this change the wave and reflection?

(2 pts):

4. Reset the damping to 10, click on [pic] and click [pic]. Now play around with changing the frequency of the wave. How does the wave change with a greater frequency? (2 pts):

5. Now reset the frequency to 50 and keep damping at 10. Play around with changing the amplitude. How does greater amplitude change the wave? (1 pt)

6. Try adjusting the tension in the string. DO NOT change anything else! What do you notice about the wave in higher tensions vs. lower tensions (2 pts):

You will now need to take measurements. To do this you must turn on the rulers and timer. Adjust the amplitude and frequency to what the table specifies. Once the simulator is moving, pause it. Then use the step button to move your wave until the oscillator has gone through a full cycle (one full up, down, and back up movement). You can track this with the green dots.

You will then be able to measure both the time of the wave (called period) and the wavelength as shown here.

7. Take measurements of both the wavelength and period of the wave for the following settings: (12 pts):

|Frequency |Amplitude |Time of one cycle (period in sec) |Wavelength (cm) |

|25 |50 |1 sec |66cm |

|25 |100 |3.25sec |66cm |

|50 |50 |About .49sec |33cm |

|50 |100 |About .49 sec |32cm |

|75 |50 |About .33sec |22cm |

|75 |100 |About .33sec |22cm |

8. Does changing the amplitude when the frequency is the same change either the period or the wavelength? (1 pt)perio

9. What does increasing the frequency do to the period?

(1 pt)

10. What does increasing the frequency do to the wavelength?

(1 pt)

11. Period is actually the inverse of frequency (or 1/f). What would the period be for a wave with a frequency of 200 Hz? (2 pts)

12. The speed of a wave is calculated by the formula speed = wavelength x frequency. What is the speed of your wave for the first trial above (f = 25)?

(2 pts)

Conclusion Questions: Highlight correct answer or delete the wrong answer for MC:

(1 pt EACH):

1. When a wave strikes a boundary that is more dense than the original wave medium (like the fixed end in the simulator), the wave comes back upright / inverted.

2. When a wave strikes a boundary that is less dense than the original wave medium (like the loose end in the simulator), the wave comes back upright / inverted.

3. Which of the following affects the wavelength of a wave? frequency/amplitude.

4. A wave with a shorter/longer wavelength has a higher period.

5. The speed of a wave gets larger/smaller with higher frequency waves.

6. The speed of a wave gets larger/smaller with longer wavelength waves.

7. A wave with peaks separated by 34 cm has a wavelength of

8. Imagine standing near the door of a dog house. If a puppy comes running out every three seconds, what would the period of the exiting puppies be?

9. Considering the above, how many puppies (or fraction of a puppy) exit every second? (This is frequency)

10. If a certain wave has a new wave crest created every 2.5 seconds, the period is

11. What is the frequency of the wave described above in #8?

12. What is the speed of a wave which has a frequency of 440 and a wavelength of 0.75 meters?

BONUS (+2) The answer to number question # 12 above is the speed of

(You will have to look it up online!)

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Or wavelength

Tommy hartzfeld

wavelength = _______ cm

Is a long wave that is controlled by your movement of yourself creating and sending a wave pulse towards one fixed end holding it still.

I created a endless wave, the dampinig is acting as no resistance against it therefore its endlessly in motion

The waves are not bouncing back towards where they start and with a higher frequency it creates a smaller wave length at

The higher the amplitude the greater the wave height.

Period = _______ seconds

The time cycle period

Makes it shorter

Makes it shorter

The speed in which the waves travel.

200

1650

Sound wave in air

34cm

3sec

1/3 .333

5sec

.333

330m/s

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