(a) What is the intensity in W/m of a laser beam used to burn away cancerous tissue that, when 90.0% absorbed, puts 540 J of energy into a circular spot 2.2 mm in diameter in 1.5 s? Hint: The laser is a collimated beam of light and does not produce a spherical wave. w/m2 (b) Reflect on how this intensity compares to the average intensity of sunlight (about 1W/m) and the implications that would have if the laser beam entered your eye. Note how your answer depends on the time duration of the exposure. The intensity of a laser is about damaging if they enter your eye. + times that of the sun, so clearly lasers can be very

(a) What is the intensity in W/m of a laser beam used to burn away cancerous tissue that, when 90.0% absorbed, puts 540 J of energy into a circular spot 2.2 mm in diameter in 1.5 s? Hint: The laser is a collimated beam of light and does not produce a spherical wave. w/m2 (b) Reflect on how this intensity compares to the average intensity of sunlight (about 1W/m) and the implications that would have if the laser beam entered your eye. Note how your answer depends on the time duration of the exposure. The intensity of a laser is about damaging if they enter your eye. + times that of the sun, so clearly lasers can be very

College Physics

11th Edition

ISBN:9781305952300

Author:Raymond A. Serway, Chris Vuille

Publisher:Raymond A. Serway, Chris Vuille

Chapter1: Units, Trigonometry. And Vectors

Section: Chapter Questions

Problem 1CQ: Estimate the order of magnitude of the length, in meters, of each of the following; (a) a mouse, (b)...

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The average intensity of sunlight on Earth’s surface is about 1000 ? ?2 ⁄ a. Calculate the solar panel area if the amount of energy that falls on it in 10 hours is 3 × 1012J.b. What intensity would such sunlight have if concentrated by a magnifying glass onto an area 100 times smaller than its own?
One of the highest power lasers in the world sits on a table. It emits pulses that last approximately 16 fs, and contain 103 mJ of energy. "fs" indicates a femtosecond, which is 10-15 seconds. a) What is the average power associated with a single pulse? b) What is the physical length of this pulse? c) When the beam exits the laser, it is approximately 30 mm in diameter. Molecules begin to ionize when applied electric fields reach approximately 8.680e+09 V/m. To what diameter must the beam be focused to reach this electric field strength?
The intensity of solar radiation at the top of the Earth's atmosphere is 1 402 W/m2. Assuming 60% of the incoming solar energy reaches the Earth's surface and you absorb 50% of the incident energy, find the amount of solar energy you absorb if you sunbathe for 64 minutes. (Suppose you cover a 1.5 m × 0.3 m section of beach blanket and the elevation angle of the Sun is 60°.)
The intensity of the Sun's radiation that reaches a particular point on Earth's atmosphere is 1.06 kW/m2. Convert this to W/cm2. Give your answer with two digits of precision.
A large fraction of the ultraviolet (UV) radiation coming from the sun is absorbed by the atmosphere. The main UV absorber in our atmosphere is ozone, O3. In particular, ozone absorbs radiation with frequencies around 9.38×1014 Hz . What is the wavelength λ of the radiation absorbed by ozone?
Betelgeuse, a red-giant star in the constellation Orion, has a peak in its radiation at a frequency of 3.09 X 10^14 Hz. What is the surface temperature of Betelgeuse?
Humans are unable to convert radiant energy from the sun into stored energy that can be usedto do work. Plants, however, obtain their energy from photosynthesis – sunlight is used toconvert carbon dioxide and water into sugars (stored as an energy source) and oxygen.Consider a leaf with a surface area of 2.5 cm2. On a sunny day it might receive sunlight withan average power per unit area of 350 W/m2. Of this incident light, only about 40% is usefulfor photosynthesis. (a) If the process was perfectly efficient (i.e. all the useful radiation was converted tostored internal energy), calculate the increase in internal energy of the leaf in aperiod of one hour. (b) In practice, the overall efficiency of the process (percentage of energy storedrelative to the total incident energy reaching the surface of the leaf) is only about6%. Discuss, in relation to the First Law of Thermodynamics, what happens to theremaining energy?
What is the intensity in W/m2 of a laser beam used to burn away cancerous tissue that, when 94.0% absorbed, puts 540 J of energy into a circular spot 2.20 mm in diameter in 4.00 s? Discuss how this intensity compares to the average intensity of sunlight (about 700 W/m2) and the implications it would have if the laser beam entered your eye. Note how your answer depends on the time duration of the exposure.
The maximum intensity of radiation emitted by a star occurs at a surface temperature of 4.3 x 104 K. a) Calculate the wavelength of the emitted radiation when the intensity is maximum. b) Calculate the ratio of the intensity radiated at a wavelength of 60.0 nm to the maximum intensity. Assume that the star radiates like an ideal blackbody.
Suppose a hot object radiates with the twice the intensity as the sun on earth, i.e. 2600W/m2. What is the energy density of this radiation?
An infrared satellite measures outgoing radiation that leaves Earth's surface through an atmospheric window. The observed spectral irradiance at a wavelength of 10 μm is 2.199×107 W m-2 m-1. What is the temperature of the surface? Give your answer in K.
Irradiation on a semitransparent medium is at a rate of 520 W/m2. If 160 W/m2 of the irradiation is reflected from the medium and 130 W/m2 is transmitted through the medium, determine the medium’s absorptivity, reflectivity, transmissivity, and emissivity.