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Chapter 32 Solutions
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- (a) The ideal size (most efficient) for a broadcast antenna with one end on the ground is onefourth the wavelength (/4) of the electromagnetic radiation being sent out. If a new radio station has such an antenna that is 50.0 m high, what frequency does it broadcast most efficiently? Is this in the AM or FM band? (b) Discuss the analogy of the fundamental resonant mode of an air column closed at one end to the resonance of currents on an antenna that is one-fourth their wavelength.arrow_forwardFigure P34.15 shows a plane electromagnetic sinusoidal wave propagating in the x direction. Suppose the wavelength is 50.0 m and the electric field vibrates in the xy plane with an amplitude of 22.0 V/m. Calculate (a) the frequency of the wave and (b) the magnetic field B when the electric field has its maximum value in the negative y direction, (c) Write an expression for B with the correct unit vector, with numerical values for Bmax, k, and , and with its magnitude in the formarrow_forwardThe Poynting vector describes a flow of energy whenever electric and magnetic fields are present. Consider a long cylindrical wire of radius r with a current I in the wire, with resistance R and voltage V. From the expressions for the electric field along the wire and the magnetic field around the wire, obtain the magnitude and direction of the Poynting vector at the surface. Show that it accounts for an energy flow into the wire from the fields around it that accounts for the Ohmic heating of the wire.arrow_forward
- A spherical interplanetary grain of dust of radius 0.2 m is at a distance r1 from the Sun. The gravitational force exerted by the Sun on the grain just balances the force due to radiation pressure from the Sun's light. (i) Assume the grain is moved to a distance 2r1 from the Sun and released. At this location, what is the net force exerted on the grain? (a) toward the Sun (b) away from the Sun (c) zero (d) impossible to determine without knowing the mass of the grain (ii) Now assume the grain is moved back to its original location at r1, compressed so that it crystallizes into a sphere with significantly higher density, and then released. In this situation, what is the net force exerted on the grain? Choose from the same possibilities as in part (i).arrow_forwardA microwave source produces pulses of 20.0-GHz radiation, with each pulse lasting 1.00 ns. A parabolic reflector with a face area of radius 6.00 cm is used to focus the micro-waves into a parallel beam of radiation as shown in Figure P24.72. The average power during each pulse is 25.0 kW. (a) What is the wavelength of these microwaves? (b) What is the total energy contained in each pulse? (c) Compute the average energy density inside each pulse. (d) Determine the amplitude of the electric and magnetic fields in these microwaves. (e) Assuming that this pulsed beam strikes an absorbing surface, compute the force exerted on the surface during the 1.00-ns duration of each pulse.arrow_forwardA plane electromagnetic wave of frequency 20 GHz moves in the positive y-axis direction such that its electric field is pointed along the z-axis. The amplitude of the electric field is 10 V/m. The start of time is chosen so that at t = 0, the electric field has a value 10 V/m at the origin. (a) Write the wave function that will describe the electric field wave, (b) Find the wave function that will describe the associated magnetic field wave.arrow_forward
- Ultraviolet light is typically divided into threecategories. UV-A, with wavelengths between 400 nm and 320 nm,has been linked with malignant melanomas. UV-B radiation,which is the primary cause of sunburn and other skin cancers,has wavelengths between 320 nm and 280 nm. Finally, the regionknown as UV-C extends to wavelengths of 100 nm. (a) Find therange of frequencies for UV-B radiation. (b) In which of thesethree categories does radiation with a frequency of 7.9 * 1014 Hzbelong?arrow_forwardThe wavelength of light emitted by a Carbon Dioxide laser is 10.6 micrometers. a) What is the frequency of the light and b) What part of the EM Spectrum is it. Look in the middle of the chart for the Type of Radiation where you see Radio Waves, Microwaves... etc. to make your selection? c) What are some detectable Objects at this frequency.arrow_forward1) A certain star is 16.1 million light-years from Earth. The intensity of the light that reaches Earth from the star is 3.20 × 10−21 W/m2. At what rate does the star radiate EM energy?2) The intensity of solar radiation that falls on a detector on Earth is 1.00 kW/m2. The detector is a square that measures 5.11 m on a side and the normal to its surface makes an angle of 30.0° with respect to the Sun’s radiation. How long will it take for the detector to measure 424 kJ of energy?3) Unpolarized light passes through two ideal polarizers in turn with polarization axes at 43.9° to each other. What is the fraction of the incident light intensity that is transmitted?arrow_forward
- The Sun generates spherical waves of light. If you determine the peak electric field of the sunlight waves to be E a distance r from the Sun, what is the peak electric field a distance of 2r from the Sun?Options are ;arrow_forward1. Which part of the electromagnetic spectrum has a higher frequency than ultraviolet waves? a. infrared b. microwaves c. x-rays d. none of these 2. Which part of the electromagnetic spectrum has a longer wavelength than visible light? a. gamma rays b. radio waves c. ultraviolet waves d. X-rays 3. Which of the given regions of the electromagnetic spectrum are arranged according to decreasing wavelength? a. X-rays, gamma rays, ultraviolet, infrared b. microwaves, infrared, gamma rays, X-rays c. gamma rays, X-rays, microwaves, radio waves d. radio waves, microwaves, X-rays, gamma raysarrow_forward26 - Which of the following is incorrect? a) The energy of an electromagnetic radiation can be found by E = hv (h = plank constant, v, frequency). B) At any given point, more waves pass through the smaller wavelength than the larger wavelength radiation in one second. NS) The smaller the wavelength, the greater the energy of the radiation. D) Radiation that glows in yellow has a higher energy than radiation that glows in blue. TO) The velocity of all radiation with different energies under vacuum is equal to the speed of light.arrow_forward
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