Name Class Date. Circle the letter of the best answer for each question.

Transcription

1 Skills Worksheet Directed Reading B Section: The Electromagnetic Spectrum CHARACTERISTICS OF EM WAVES 1. At what speed do EM waves travel in a vacuum? a. 3,000,000 km/s b. 3,000,000 km/min c. 300,000 km/s d. 300,000 km/min 2. What is the way to find the speed of a wave? a. Divide wavelength by frequency. b. Multiply wavelength by frequency. c. Divide frequency by wavelength. d. Add frequency and wavelength. 3. What is the entire range of EM waves called? a. a rainbow b. visible light c. electricity d. the electromagnetic spectrum 4. How are electromagnetic waves arranged? a. by speed b. by amplitude c. by wavelength or frequency d. by usefulness Holt Science and Technology 22 The Nature of Light

2 Read the words in the box. Read the sentences. Fill in each blank with the word or phrase that best completes the sentence. gamma rays infrared waves ultraviolet waves X rays 5. EM waves whose name means below red are. 6. EM waves that are produced by some nuclear reactions are 7. EM waves discovered in 1895 are 8. EM waves whose name means beyond violet are RADIO WAVES 9. Which EM waves have some of the longest wavelengths and lowest frequencies? a. microwaves b. radio waves c. sound waves d. broadcasting waves Broadcasting Radio Signals 10. What is changing amplitude or frequency called? a. amplification b. encoding c. modulation d. moderation Holt Science and Technology 23 The Nature of Light

3 Comparing AM and FM Radio Waves 11. Which affects FM radio waves less than AM radio waves? a. electrical noise c. sunlight b. temperature d. pressure Radio Waves and Television 12. Which of EM waves are used to send television signals? a. microwaves c. sound waves b. radio waves d. broadcasting waves MICROWAVES 13. How does a magnetron produce microwaves in a microwave oven? a. by magnetizing charged particles b. by slowing down charged particles c. by speeding up charged particles d. by speeding up magnetized particles Microwaves and Communication 14. Which EM waves are used by cellular phones? a. radio waves b. microwaves c. gamma rays d. satellite waves Radar 15. What can a police officer use radar to check? a. the speed and location of objects b. the size of objects c. the weight of objects d. the color of objects Holt Science and Technology 24 The Nature of Light

4 INFRARED WAVES 16. Which gives off infrared waves? a. only things on Earth c. only buildings and trees b. only the sun d. almost all things 17. The amount of infrared waves an object gives off depends on what? a. the wave s speed c. the object s weight b. the wave s color d. the object s temperature VISIBLE LIGHT 18. What is the range of wavelengths and frequencies that humans can see? a. infrared waves b. visible light c. ultraviolet light Visible Light from the Sun 19. What is the visible light of all wavelengths combined? a. white light c. ultraviolet light Colors of Light 20. What does ROY G. BiV stand for? a. the last letter of each color of visible light b. the first letter of each color of visible light c. the first letter of each type of EM wave d. the person who discovered visible light Holt Science and Technology 25 The Nature of Light

5 Read the description. Then, draw a line from the dot next to each description to the matching word. 21. color of the longest wavelength of visible light 22. color of the shortest wavelength of visible light 23. the range of colors a. violet light b. visible spectrum c. red light ULTRAVIOLET LIGHT Bad Effects 24. Which EM waves can cause sunburn, skin cancer, and wrinkles? a. visible light waves c. ultraviolet waves 25. How can you protect your skin from getting too much ultraviolet light? a. Use tanning cream. b. Use sunscreen with a high SPF. c. Use sunscreen with a low SPF. d. Use body lotion. Good Effects 26. Which EM waves can kill bacteria on food and surgical tools? a. visible light waves c. ultraviolet waves d. radio waves Holt Science and Technology 26 The Nature of Light

6 27. What do skin cells produce when exposed to a little ultraviolet light? a. vitamin D b. freckles c. calcium d. vitamin C X RAYS AND GAMMA RAYS X Rays 28. Which EM waves are used to see inside suitcases without opening them? a. microwaves c. gamma rays 29. Why are X rays useful in the medical field? a. X rays are stopped by most materials. b. X rays can pass through many materials. c. X rays are invisible. have long wavelengths. 30. What can too much exposure to X rays do? a. cause sunburn b. ruin a lead apron c. overcook food d. damage or kill living cells Holt Science and Technology 27 The Nature of Light

7 31. What material can X rays NOT pass through? a. skin b. lead c. muscles d. clothing Gamma Rays 32. How do doctors use gamma rays? a. to take X rays b. to kill cancer cells c. to take temperatures d. to do surgery 33. What is a bad effect of using gamma rays to treat cancer? a. The tumors may get larger. b. The skin may get a sunburn. c. Healthy cells may be killed. d. Unhealthy cells may be killed. 34. Gamma rays kill what in food? a. harmful bacteria b. calories c. taste d. color Holt Science and Technology 28 The Nature of Light