He-Ne (Helium-Neon) lasers are often used in physics demonstrations. Mine is labelled as about 5 mW and 650 nm. Let's approximate that the light is spread over a cylindrical beam about 1 mm in diameter. a. What's the intensity of the beam (approximately)? b. What are the maximum electric and magnetic field values? What are the average values? Explain briefly why those are different. c. What's the average energy density of the beam? d. What's the frequency of the EM wave?

He-Ne (Helium-Neon) lasers are often used in physics demonstrations. Mine is labelled as about 5 mW and 650 nm. Let's approximate that the light is spread over a cylindrical beam about 1 mm in diameter. a. What's the intensity of the beam (approximately)? b. What are the maximum electric and magnetic field values? What are the average values? Explain briefly why those are different. c. What's the average energy density of the beam? d. What's the frequency of the EM wave?

University Physics Volume 2

18th Edition

ISBN:9781938168161

Author:OpenStax

Publisher:OpenStax

Chapter16: Electromagnetic Waves

Section: Chapter Questions

Problem 63P: A 2.50-rn-diameter university communications satellite dish receives TV sigia1s that have a maximum...

See similar textbooks

Similar questions

A 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?
Q3] A pulse radar system transmits 100 kW power through an isotropic antenna and receives 1 mW power. Assume o = 1 m2 and operating frequency=1 GHz. a) What is the range of the target? b) Discuss, mathematically, how you can increase the range by a factor 2 without changing the abovementioned radar figures.
An AM radio transmitter broadcasts 45 kW of power uniformly in all directions.Randomized VariablesP = 45 kWd = 29 km Part (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 29 km away? Part (b) What is the maximum electric field strength at this distance, in N/C?
An EM wave in free space has a wavelength of 670nm. (a) What is its frequency? (b) How would we classify it?
(a) What is the wavelength (in meters) of a 93.3 MHz Radio wave frequency? (b) What is the frequency (in Hz) of an x-ray beam with a wavelength of 0.0100 nm?
A radio antenna broadcasts a 1.0 MHz radio wave with 25 kW of power. Assume that the radiation is emitted uniformly in all directions.a. What is the wave’s intensity 30 km from the antenna?b. What is the electric field amplitude at this distance?
The radio station broadcasts at a frequency of 100 MHz. What is the wavelength of the radio waves it emits? (a) Write first the formulae with no numbers, (b) correctly label each quantity, (c) then plug the numbers and solve it.
A certain radar installation that is used to track airplanes trasmits electromagnetic radiation with a wavelength of 3cm. (A) what is the frequency? (B) What time is required for a pulse of radar waves to reach an airplane 5 km away and return?
Answer the following A. A comet has just passed the Earth and its peak emission is observed at 15000 nm. Determine in which region of the electromagnetic spectrum (e.g. X-ray, infrared, visible, ultraviolet, ...) the peak emission wavelength resides. What is the temperature of the comet? B. Within the Solar System, a convenient unit of measurement is the Earth-Sun distance, called an astronomical unit (AU). For bigger distances, we use the light year (LY), the distance that light travels in one year. We can expand our lingo to include other measures of distance, for example, light days, light minutes, and light hours. Starting with the values you can look up in the Appendices for the speed of light and the astronomical unit, calculate how many “light minutes” there are in 1 AU. C. What is the observable universe? How big is it?
What is the minimum angular spread of a 633-nmwavelength He-Ne laser beam that is originally 1.00 mm indiameter?(b) If this laser is aimed at a mountain cliff 15.0 km away, howbig will the illuminated spot be?(c) How big a spot would be illuminated on the Moon,neglecting atmospheric effects? (This might be done to hit acorner reflector to measure the round-trip time and, hence,distance.) Explicitly show how you follow the steps inProblem-Solving Strategies for Wave Optics
Some of the most powerful lasers in the worldare used in nuclear fusion experiments. The NOVA laser produced40.0 kJ of energy in a pulse that lasted 2.50 ns, and the NIF laserproduces a 20.0-ns pulse with 4.20 MJ of energy. (a) Which laserproduces more energy in each pulse? (b) Which laser produces thegreater average power during each pulse? (c) If the beam diametersare the same, which laser produces the greater average intensity?
A sinusoidal plane electromagnetic wave of frequency 20 GHz moves in the positive y direction and its electric field is directed 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)k at the origin. a. Write the function that describes the electric field of the wave as a function of position y and time t. Hint: Among other things, you need to decide whether to use a cosine or sine function, and whether a negative sign is needed inside and/or outside the sine/cosine function. b. Explain why the electric field is not a function of the x or z coordinate. c. Find the function that describes magnetic field of the wave as a function of position y and time t.