Marr College Physics S3 Physics Waves and Radiation Homework Exercises

Transcription

1 Marr College Physics S3 Physics Waves and Radiation Homework Exercises Page 1

2 Exercise 1 wave characteristics 1. Copy and complete the following: With a _ wave, the particles vibrate at 90 to the direction of wave transfer. With a wave, the particles vibrate along the same line as the direction of energy transfer. 2. For the images shown below, identify which one shows a transverse wave, and which one shows a longitudinal wave. image (a) image (b) 3. Give an example of: (a) a transverse wave (b) a longitudinal wave. 4. State what is meant by the frequency of a wave. 5. A student measures the frequency of a sound wave as 440 Hz. State how many waves are produced in one second. Page 2

3 6. A student is relaxing on Troon beach and is counting waves approaching the shore. She counts 10 waves in 50 seconds. Calculate the frequency of the waves. 7. Copy the diagram below. On the diagram, label with an arrow, distances that represent: (a) The wavelength (b) The amplitude 8. A water wave travels a distance of 150 m in a time of 10 s. Calculate the speed of the water wave. 9. A sound wave has a frequency of 170 Hz and a wavelength of 2 0 m. Calculate the speed of the wave. End of exercise 1 Page 3

4 Exercise 2 Sound 1. Copy and complete the following: To produce sound an object must _. Sound waves transfer. 2. A student investigates sound waves using a microphone connected to an oscilloscope. She sings a variety of notes into the microphone. The oscilloscope signals are shown below: State which signal, A, B, C or D represents: (a) The highest frequency sound; (b) The loudest sound. 3. Describe a method to measure the speed of sound in air. Your description should include: (a) A labelled diagram of apparatus and how it is used; (b) The measurements taken; (c) The calculations involved. Page 4

5 4. A spectator is watching a golfer about to strike the ball with the golf club. The spectator is around 400 metres away from the golfer. The spectator notices a delay between seeing the golfer striking the ball and hearing the club striking the ball. Explain why the spectator notices this delay. 5. A student carries out an experiment to measure the speed of sound in air. The student makes the following measurements: Distance that sound travelled: 1 60 metres Time for sound to travel this distance: seconds (a) Use the measurements to calculate the speed of sound in air from this experiment. (b) Comment on how well your answer to (a) compares to the accepted value of 340 m s -1. (c) Suggest a possible way for the student to improve the accuracy of the experiment. 6. Sound travels at 340 m s -1 through air. Calculate the time taken for sound to travel a distance of 600 m in air. 7. A student is at a fireworks display. The bang from a rocket is heard 2 8 seconds after it is seen to explode. Calculate the distance between the rocket and the student when it exploded. (Use the speed of sound in air value of 340 m s -1 ) End of Exercise 2 Page 5

6 Exercise 3 using sound 1. Copy and complete the following: Sound can travel through, liquids and _. Sound cannot travel through a. 2. State the lowest and the highest frequency that humans can hear. 3. A student sets up an experiment to investigate sound using an electric bell inside a bell jar, connected to a vacuum pump. (a) The bell is switched on and the air is gradually pumped out from within the bell jar. Describe what the student would hear as more and more air is pumped out from within the bell jar. (b) The science fiction horror movie Alien used the advertising tagline In space, no-one can hear you scream. Explain why this is the case. Page 6

7 4. State the same given to frequencies higher than the upper limit of human hearing. 5. Describe one use of ultrasound in medicine. 6. Ultrasound is used in the sonar systems of fishing boats to detect the bottom of the sea bed, or shoals of fish. The sonar detector uses ultrasound pulses which are transmitted from the boat. The ultrasound pulses then travel through the water, reflect off the sea bed and are received by the ship. The time taken for the ultrasound pulse to be transmitted and received is 0 82 s. (a) Calculate the time taken for the ultrasound pulse to travel from the ship to the sea bed. (b) Calculate the depth of the sea. (Use speed of sound in water as 1500 m s -1 ). (c) The ship moves to deeper water. Suggest a time for the ultrasound signal to be transmitted and received. 7. State the unit of sound level. Page 7

8 8. Copy and complete the following table: Source of Noise whisper normal conversation pneumatic drill Sound level 0 db 60 db 9. Noise pollution can be a problem. (a) State two examples of noise pollution. (b) Describe the risk of long-time exposure to excessive noise. (c) Describe how a person can reduce the risk of exposure to excessive noise levels. End of Exercise 3 Page 8

9 Exercise 4 electromagnetic spectrum 1. Copy the table shown below: Name of wave band Possible Detector Useful Application Radio I.R. U.V. Diode probe Sterilising plastic syringes. (a) Complete the name of waveband row (b) For each type of wave, name a device which can absorb some of the waves to detect or measure them. Enter this information in the possible detector row. (c) For each band name an application and complete the third row in the table. 2. Some electromagnetic radiation can be hazardous. (a) State the main long term danger of overexposure to ultraviolet radiation. (b) State how the risk of this danger could be minimised. 3. Remote controls use infrared signals. Infrared signals travel at m s -1 through air. Calculate how long it takes for a signal sent from a remote control to arrive at the sensor on a TV which is 3m away. 4. All radio waves travel at m/s in air. Radio Scotland broadcasts an FM signal on 94 3 MHz. (1 MHz = Hz) Calculate the wavelength of this signal. End of Exercise 4 Page 9

10 Exercise 5 - Refraction 1. Describe what is meant by refraction of light. 2. Draw a convex lens and show how it affects parallel rays of light. 3. Draw a concave lens and show how it affects parallel rays of light. 4. Copy and complete the eye diagram to show how a healthy eye would focus the rays of light. 5. Copy the table below, and fill in the blanks to give information about short & long sight: EYE DEFECT Short sight VISION PROBLEM CORRECTION LENS Long sight 6. Copy and complete the eye diagram to show how the eye of a shortsighted person would focus the rays of light, if they are not wearing glasses. Page 10

11 7. Copy and complete the diagram to show how the the correct lens is used, in front of the eye, of a long-sighted person, to enable them to focus on a close object. End of Exercise 5 Page 11

12 Exercise 6 nuclear radiation 1. A diagram of an atom is shown below. neutron X Y Identify the particles X and Y and their charges. 2. Copy and complete the following table about nuclear radiation. Name of Radiation Symbol What it is alpha What it is absorbed by Thin paper, skin, a few cm of air beta high energy electron gamma γ 3. Sources of nuclear radiation are both natural and human-made. (a) List three natural sources of nuclear radiation. (b) List three human-made sources of nuclear radiation. Page 12

13 4. Using nuclear fuel to generate electricity has advantages and disadvantages. (a) State and explain two advantages of using nuclear fuel to generate electricity. (b) State and explain two disadvantages of using nuclear fuel to generate electricity. 5. Describe a medical use of nuclear radiation. 6. Describe a use of nuclear radiation in an industry other than medicine. End of Exercise 6 Page 13