When the Voyager 2 spacecraft passed Neptune in 1989, it was 4.5 × 109 km from the earth. Its radio transmitter, with which it sent back data and images, broadcast with a mere 21 W of power. Assuming that the transmitter broadcast equally in all directions,
a. What signal intensity was received on the earth?
b. What electric field amplitude was detected?
(The received signal was slightly stronger than your result because the spacecraft used a directional antenna.)
Want to see the full answer?
Check out a sample textbook solutionChapter 25 Solutions
College Physics: A Strategic Approach Technology Update, Books A La Carte Edition (3rd Edition)
Additional Science Textbook Solutions
Essential University Physics: Volume 1 (3rd Edition)
University Physics with Modern Physics (14th Edition)
College Physics
Conceptual Integrated Science
Lecture- Tutorials for Introductory Astronomy
- An electron in a TV CRT moves with a speed of 6.0107 m/s, in a direction perpendicular to Earth's field, which has a strength of 5.0105 T. (a) What strength electric field must be applied perpendicular to the Earth’s field to make the election moves in a straight line? (b) If this is done between plates separated by 1.00 cm, what is the voltage applied? (Note that TVs are usually surrounded by a ferromagnetic material to shield against external magnetic fields and avoid the need for such a collection,)arrow_forwardA certain 60.0-Hz ac power line radiates an electromagnetic wave having a maximum electric field strength of 13.0 kV/m. (a) What is the wavelength of this very-low-frequency electromagnetic wave? (b) What type of electromagnetic radiation is this wave (b) What is its maximum magnetic field strength?arrow_forwardA 2.50-rn-diameter university communications satellite dish receives TV sigia1s that have a maximum electric field strength (for one channel) of 7.50V/m (see below). (a) What is the intensity of this wave? (b) What is the power received by the antenna? (C) If the orbiting satellite broadcasts uniformly over an area of 1.501013m2 (a large fraction of North America), how much power does it radiate?arrow_forward
- If you wish to detect details of the size of atoms (about 0.2 nm) with electromagnetic radiation, it must have a wavelength of about this size. (a) What is its frequency? (b) What type of electromagnetic radiation might this be?arrow_forwardUnreasonable results Frustrated by the small Hall voltage obtained in blood flow measurements, a medical physicist decides to increase the applied magnetic field strength to get a 0.500-V output for blood moving at 30.0 cm/s in a 1.50-cm-diameter vessel. (a) What magnetic field strength is needed? (b) What is unreasonable about this result? (C) Which premise is responsible?arrow_forward(a) A jet airplane with a 75.0 m wingspan is flying at 280 m/s. What emf is induced between wing tips if the vertical component 01 the Earth’s field is 3.00105T ? (b) Is an emf of this magnitude likely to have any consequences? Explain.arrow_forward
- Professor Edward Ney was the founder of infrared astronomy at the University of Minnesota. In his later years, he wore an artificial pacemaker. Always an experimentalist, Ney often held a strong laboratory magnet near his chest to see what effect it had on his pacemaker. Perhaps he was using the magnet to throw switches that control different modes of operation. An admiring student (without an artificial pacemaker) thought it would be fun to imitate this great man by holding a strong magnet to his own chest. The natural pacemaker of the heart (known as the sinoatrial node) carries a current of about 0.5 mA. Estimate the magnetic force exerted on a natural pacemaker by a strong magnet held to the chest. How do you think the student might have felt during the experiment? Explain your geometric assumptions. Hints: See Table 30.1 (page 941) to estimate the magnetic field, and assume the field is roughly uniform. Use Figure P30.58 to estimate the size of the sinoatrial node; your heart is about the size of your fist. FIGURE P30.58arrow_forwardAn AM radio transmitter broadcasts 50.0 kW of power uniformly in all directions. (a) Assuming all of the radio waves that strike the ground are completely absorbed, and that there is no absorption by the atmosphere or other objects, what Is the intensity 30.0 km away? (Hint: Half the power will be spread over the area of a hemisphere.) (b) What is the maximum electric field strength at this distance?arrow_forwardSuppose the maximum safe intensity of microwaves for human exposure is taken to be 1,00 W/m2. (a) If a radar unit leaks 10.0 W of microwaves (other than those sent by its antenna) uniformly in all directions, how far away must you be to be exposed to an intensity considered to be safe? Assume that the power spreads uniformly over the area of a sphere with no complications from absorption or reflection, (b) What is the maximum electric field strength at the safe intensity? (Note that early radar units leaked more than modem ones do. This caused identifiable health problems, such as cataracts, for people who worked near them.)arrow_forward
- Suppose the maximum safe intensity of microwaves for human exposure is taken to be 1.00 W/m2. (a) If a radar unit leaks 10.0 W of microwaves (other than those sent by its antenna) uniformly in all directions, how far away must you be to be exposed to an intensity considered to be safe? Assume that the power spreads uniformly over the area of a sphere with no complications from absorption or reflection. (b) What is the maximum electric field strength at the safe intensity? (Note that early radar units leaked more than modern ones do. This caused identi?able health problems, such as cataracts, for people who worked near them.)arrow_forwardA dish antenna with a diameter of 20.0 m receives (at normal incidence) a radio signal from a distant source, as shown in Figure P21.73. The radio signal is a continuous sinusoidal wave with amplitude Emax = 0.20 V/m. Assume the antenna absorbs all the radiation that falls on the dish. (a) What is the amplitude of the magnetic field in this Figure P21.73 wave? (b) What is the intensity of the radiation received by the antenna? (c) What is the power received by the antenna?arrow_forwardAn incandescent light bulb emits only 2.6 W of its power as visible light. What is the rms electric field of the emitted light at a distance of 3.0 m from the bulb?arrow_forward
- Physics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage LearningCollege PhysicsPhysicsISBN:9781938168000Author:Paul Peter Urone, Roger HinrichsPublisher:OpenStax College
- Principles of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningCollege PhysicsPhysicsISBN:9781305952300Author:Raymond A. Serway, Chris VuillePublisher:Cengage Learning