Background: The Electromagnetic Spectrum Wavelength (λ) in meters wavelength decreasing 10 4 10 2 10 0 10-2 10-4 10-6 10-8 10-10 10-12 10-14 microwaves ultraviolet Gamma rays Radio waves AM 10 4 Shortwave 10 6 10 8 FM, TV Infrared X-rays 10 10 10 12 10 14 10 16 10 18 10 20 10 22 Frequency (f) in Hertz (Hz) frequency increasing Speed of light = 3.00 x 10 8 m/s R O Y G B I V 7.50 x 10-7 m Visible Light 3.80 x 10-7 m 1. There are several ways to describe the properties of waves, including wavelength, frequency, energy, speed, and amplitude. Which property is the same for all electromagnetic waves? Name Letter Value with units 2. Find the other two factors in the diagram above. Write the name, the letter used to represent it, and its units. Name Letter Unit Name Letter Unit 1
Background: The Electromagnetic Spectrum, continued Wavelength (λ) in meters wavelength decreasing 10 4 10 2 10 0 10-2 10-4 10-6 10-8 10-10 10-12 10-14 microwaves ultraviolet Gamma rays Radio waves 10 AM 4 Shortwave 10 6 10 8 FM, TV Infrared 10 10 10 12 10 14 10 16 X-rays 10 18 10 20 10 22 Frequency (f) in Hertz (Hz) frequency increasing Speed of light = 3.00 x 10 8 m/s R O Y G B I V 7.50 x 10-7 m Visible Light 3.80 x 10-7 m 3. Write the name of one kind of wave with a high frequency. 4. What is the approximate frequency of this wave (include units)? 5. What is the approximate wavelength of this wave (include units)? 6. What is the equation that relates frequency and wavelength? 7. Draw a wave that is several wavelengths long and label the trough and crest of one wavelength. 2
Background: The Electromagnetic Spectrum, continued As applicable, show your calculations and include units in your answer. 1. If a wave of red light has a wavelength of 6.7 x 10-7 m, what is the frequency of the red wave? 2. If a wave of violet light has a frequency of 7.6 x 10 14 Hz, what is the wavelength of the violet wave? 3. If a wave of blue light has a wavelength of 4.6 x 10-7 m, what is the frequency of the blue wave? 4. If a wave of yellow light has a frequency of 5.1 x 10 14 Hz, what is the wavelength of the yellow wave? 5. Which color wave from the visible spectrum has the smallest wavelength? 6. Which color wave from the visible spectrum has the longest wavelength? 3
Part I: Plan Your Investigation 1. My Question of Inquiry 2. Tools and Equipment Tool Purpose 3. Safety Precautions 4. Procedure List the steps of your procedure. Use additional paper, as needed. You will use the data charts provided to record the emission spectra of elements in the gas tubes. 4
Part II: Implement Your Investigation Data Collection and Results 5
Part II: Implement Your Investigation, continued Analysis 1. Which element had the most emission spectrum lines? 2. Which element had the fewest emission spectrum lines? 3. Choose one of the elements that you observed in the gas tubes. Try to pick the one that you think had the clearest, brightest lines: Element: A. Draw the brightest line from this element on the data chart above. B. What is the approximate wavelength of this light? Include units. C. What is the frequency of this light? Include units and show calculations. D. What is the energy of a photon of this light? Include units and show calculations. 6
Reflection and Conclusions 1. Explain how you answered your question of inquiry. 2. What causes the emission spectra that you observed through the spectroscope? 3. Why can you only see these lines when electricity is applied to the light bulb? 4. What type of data did you collect, qualitative or quantitative? Justify your answer. 5. Using all of the following terms, develop a graphic organizer based on what you have learned in this Explore. Use another sheet of paper, if needed. Terms: Electromagnetic spectrum, electromagnetic wave, crest, trough, emission spectra, frequency, wavelength, speed of light, Planck s constant, energy, Hertz, meter, joule, second, electrons, energy levels. 7