Astronomy Study Guide Unit 4 4 4 When a light ray travels from water to air which way does its direction change A It bends away from the normal to the water surface 4 4 The index of refraction of a certain type of glass is 1 5 Given that speed of light in vacuum is 300 00 km s what is the speed of light in the glass A 200 000 km s divide speed of light in a vacuum by the index refraction 4 4 When a light rat travels from air to glass which way does its direction change A It bends toward the normal to the glass surface 4 5 The index of refraction of water is greater than air When light passes from water to air at an angle the light is A Bent away from the normal light is traveling from more optically dense to less optically dense material 4 5 From the figure we know that angles A1 and A2 are related by A A1 A2 4 5 surface and that part of the ray is reflected and part refracted as shown in the figure Suppose the index of refraction of the second material is greater than that of the first What is the prediction of the law of reflection for the reflected ray Suppose a light ray is incident on a A Angle of incidence equals angle of reflection 4 5 When the angle of incidence increases the angle of reflection A Increases by the same amount 4 5 The index of refraction of water is greater than air When light passes from air to water at an angle the light is A Bent towards the normal 4 6A The magnifying power of a telescope is A The ratio of the angular size of an object when viewed with the telescope to the angular size without the telescope 4 6B The light gathering power of a telescope increases as the aperture of the telescope is enlarged A correct light gathering is proportional to the area of the objective 4 6B Which has the larger light gathering power A A telescope of 9cm diameter focal length of 150 cm largest diameter largest area 4 6C The resolving power of a telescope is A a measure of the minimum separation of two stars that can be detected with the telescope 4 6C The minimum angular separation of two stars that can be seen be a particular telescope is called the power of that telescope A resolving 4 9 The structure of most images of stars seen in photographs made through a telescope is caused by This excludes the Sun and a few nearby stars A both b c telescope size film system 4 9 causes even perfect lenses or mirrors to form the image of star as a disk surrounded by faint rings A diffraction 4 10 Suppose you have a telescope with a resolution of 5sec of arc Could you resolve two stars if Case 1 stars are 3 sec of arc apart Case 2 stars are 4 sec of arc apart A No for both 1 and 2 resolution of a telescope is the smallest angle two point objects can be separated and still be distinguished as two objects 4 10 Light from a star enters a telescope The light entering one side interferes with light from the other side This is called A diffraction 4 10 The resolution or resolving power of a telescope is A the smallest angle two point objects can be separated and still be distinguished as two objects 4 10 Suppose you have a telescope with a resolution of 5sec of arc Could you resolve two stars if Case 1 stars are 7 sec of arc apart Case 2 stars are 14 sec of arc apart 4 10 Diffraction of light is most easily explained by considering light as a particle 4 10 Using a telescope with a resolution of 3 can two stars be resolved if they are separated by 1 1 2 9 A Yes for both 1 and 2 A incorrect A No for 1 yes for 2 4 10 The smallest angle two point objects can be separated and still be distinguished as two objects by a telescope is the of the telescope A resolution 4 11 The major cause of fuzziness in an image of a star seen through a telescope is usually the result of A atmospheric turbulence 4 11 causes even perfect lenses or mirrors to form images of stars as disks surrounded by faint rings 4 11 The ideal image of a star in a telescope is a small disk surrounded by faint rings The disk is called the disk A diffraction A Airy 4 11 The diffraction pattern of a star produced in a telescope appears as A A central disk surrounded by faint rings 4 12 The cross hair pattern often seen in star photographs where the image has been overexposed is caused by A diffraction from the secondary mirror support 4 12 The irregular spikes often seen in star photographs where the image has been overexposed is caused by A both B and D atmosphere motion irregularities in the telescope 4 12 The irregular spikes often seen in star photographs where the image has been overexposed is caused by A both C and D atmosphere motion imperfections in the telescope 4 12 The circular ring which often surrounds the overexposed photographic image of a star is called A halation ring 4 12 photograph of an overexposed star image The round disk is caused in principle by F1 consider the following A diffraction on the edges of the round telescope 4 12 refer to F1 above The cross is caused by A diffraction of the secondary mirror s supporting structure 4 12 caused by reflection off of the back of the photographic plate F2 Which effect if any is A B 4 13A The velocity of a wave is A Distance it travels per unit time 4 13B The frequency of a wave is A The number of times per time interval that wavefronts pass the observer 4 13C The wavelength of a wave is A The characteristic length of the disturbance 4 13D Which of the following differentiates the particle aspect of light from its wave aspect A comes in discrete packets 4 13E The discrete units of light are called photons 4 13E The discrete units of light are called waves A correct A incorrect A 3 x 10 10 cm s A 3 x 10 8 m s A 3 x 10 5 km s 4 14 The speed of light in a vacuum is 4 14 The speed of light in a vacuum is 4 14 The speed of light in a vacuum is 4 15 In a wave the vibrating substance vibrates along the direction the wave is moving A longitudinal transverse waves vibrate peroendicular to the direction of propagation 4 15 If L is the wavelength of a wave f the wave s frequency and c the wave s speed then 4 16A The array of colors in a light beam …