HW37Due: 11:59pm on Tuesday, December 8, 2009 Note: To understand how points are awarded, read your instructor's Grading Policy. [Return to Standard Assignment View] Exercise 24.36 A capacitor is formed from two concentric spherical conducting shells separated by vacuum. The inner sphere has radius 10.0 , and the outer sphere has radius 16.5 . A potential difference of 110 is applied to the capacitor. Part A What is the energy density at = 10.1 ANSWER: −5 = 3.32×10 Correct , just outside the inner sphere? Part B What is the energy density at ANSWER: −6 = 4.77×10 Correct = 16.4 , just inside the outer sphere? Part C For a parallel-plate capacitor the energy density is uniform in the region between the plates, except near the edges of the plates. Is this also true for a spherical capacitor? ANSWER: Yes No Correct Exercise 30.14 is another toroid problem in which you are asked to assume that the B field strength within the toroid is constant. If you calculate the flux without making this approximation (assume a square cross-section for the toroid), you will find that the difference between the exact flux and the approximate flux is 1% or less. GBA Exercise 30.14 An air-filled toroidal solenoid has 360 turns of wire, a mean radius of 15.0 Part A If the current is 6.00 ANSWER: , calculate the magnetic field in the solenoid. −3 = 2.88×10 Correct , and a cross-sectional area of 4.50 . Part B Calculate the self-inductance of the solenoid. ANSWER: −5 = 7.78×10 Correct Part C Calculate the energy stored in the magnetic field. ANSWER: −3 = 1.40×10 Correct Part D Calculate the energy density in the magnetic field. ANSWER: = 3.30 Correct Part E Find the answer for part D by dividing your answer to part C by the volume of the solenoid. ANSWER: = 3.30 Correct in what direction does the electric field vector point? . in what direction does the electromagnetic wave propagate? Hint A. Based on this information. Based on this information. in what direction does the electromagnetic wave propagate? ANSWER: +x –x +y –y +z –z at a –45 angle in the xy plane Correct Part C The magnetic field vector and the direction of propagation of an electromagnetic wave are illustrated.1 Right-hand rule for electromagnetic wave velocity Hint not displayed ANSWER: +x –x +y –y +z –z at a +45 angle in the xy plane Correct Part B The electric and magnetic field vectors at a specific point in space and time are illustrated. Both information. ( vectors make 45 angles with the y axis.Electric and Magnetic Field Vectors Conceptual Question Part A The electric and magnetic field vectors at a specific point in space and time are illustrated.) Based on this and are in the xy plane. is in xz plane and in what direction does the magnetic field vector point? Hint D.0 and with a frequency of 92. Assume that the plane of the antenna loop is perpendicular to the direction of the radiation's magnetic field and that the source radiates uniformly in all directions.66×10 −9 T Correct Part B What is the maximum emf induced in the one-turn loop? ANSWER: −2 = 3. you will need to save the answer to A in your calculator and use that saved answer.) Based on this information. the rms current which results from receiving KRUD's signal must be 1/10 of the rms current which results from receiving KONG's signal (at resonance). ( makes a 45 angle with the x axis. which magnifies . To get the answer to B. this is because your answer to B depends on the small DIFFERENCE between X_C and X_L.Hint C.1 Working backward with the right-hand rule Hint not displayed ANSWER: +x –x +y –y +z –z at a +45 angle in the xz plane Correct Part D The electric field vector and the direction of propagation of an electromagnetic wave are illustrated.81×10 −12 (you will learn how to calculate this value in your lecture on the intensity of electromagnetic radiation). thus the impedance at KRUD's frequency must be 10 times the impedance at KONG's frequency (at resonance).0 2.1 Working backward with the right-hand rule Hint not displayed ANSWER: +x –x +y –y +z –z at a –45 angle in the xz plane Correct Receiving a Radio Transmission A circular loop of wire can be used as a radio antenna. Assuming the rms input EMF from both stations. Suppose that a one-turn loop antenna of diameter 16. GBA PS. What will be the maximum radiated magnetic field strength at the location of the loop receiving antenna? ANSWER: 2. is the same.0 is located .60: Since the output power is Irms^2*R. Part A Note that at a distance of 2. through the antenna.40 away from a source broadcasting with a total power of 61.0 . the timeaverage electromagnetic energy density will be 2.40 from an isotropically radiating antenna with a total power output of 61.09×10 Correct Hint for Part B of 31. ii) the ratio of the average power delivered to the resistor in response to KRUD-FM to the average power in response to KONG-FM is 1.0 .1 detest listening to KRUD-FM.00 . This limits the power received from the unwanted station. You are required to use an inductor with an inductance of 1. GBA Problem 31.19 Part A Find the capacitance ANSWER: that satisfies the design requirements. making it inaudible. 0.any rounding error in X_C. . You . .1%. which broadcasts at a frequency of 94. You received 44.40×10 −12 F Correct Part B Find the resistance ANSWER: that satisfies the design requirements. You enjoy listening to KONG-FM.00 Your goal is to design an L-R-C radio circuit with the following properties: i) It gives the maximum power response to the signal from KONG-FM. both transmitters are equally powerful. You live the same distance from both stations and as measured at your house.13 out of a possible total of 45 points.60 Designing an FM Radio Receiver. which broadcasts at a frequency of 94.150 Correct Score Summary: Your score on this assignment is 98. so both radio signals produce the same voltage of 1. 2.