A light sail is a propulsion technique that uses large sails to catch light and propel a vehicle in the vacuum of space. In a particular application, an Earth based laser illuminates such a sail perpendicularly with a beam of light of frequency 560 THz while emitting 2.7 × 1041 photons per second. Part (a) If 80% of the emitted photons reach the sail and are absorbed by it, find the resulting force, in newtons, on a sail that is momentarily at rest with respect to the laser. Part (b) Now assume the photons are reflected by the sail. Keeping all the other assumptions of part (a), find the force the light beam exerts on the sail, in newtons. Part (c) Ideally it would be best to use photons provided by natural sources to push the sail. If a star emits ns photons per second uniformly in all directions, with all the photons of frequency fs, enter an expression for the force on the sail if all the photons that strike it are reflected. Assume that the sail has an area A, is located at a distance d from the star’s center, is perpendicular to the incoming photons, and is momentarily at rest with respect to the star. Form your expression in terms of the defined quantities, h (Planck’s constant), and c (the speed of light).
Atomic Spectra
According to the Bohr model of an atom, the electron in an atom moves around a nucleus in fixed orbits with specific energies known as energy levels. The orbital energies are quantized. The electrons remain in these energy levels until they emit or absorb a photon of a particular wavelength, the quantum of energy. If the electron emits a photon, it then falls back to a lower energy level, and if it absorbs a photon, the electron rises to higher energy levels. The photons released or absorbed in these transitions of an electron are studied and analyzed on a screen as atomic spectra.
Ruby Lasers
Lasers are devices that emit light using atoms or molecules at a certain wavelength and amplify the light to produce a narrow beam of radiation. It works as per the principle of electromagnetic radiation. Their source of emission contains the same frequency and same phase. It was invented in the year 1960 by the great noble scientist, Theodore Maiman.
Balmer Series
The spectrum of frequency observed when electromagnetic radiation is emitted from an atom when it goes from higher energy state to lower state, is known as emission spectrum. This transition occurs when an excited electron moves from higher to lower state. It has many possible electron transitions and each transition has a specific energy difference.
Emission Spectrum
Every state of matter tries to be at minimum potential energy or it can be said that the atoms of element/ substance arrange themselves such that overall energy is minimum.
A light sail is a propulsion technique that uses large sails to catch light and propel a vehicle in the vacuum of space. In a particular application, an Earth based laser illuminates such a sail perpendicularly with a beam of light of frequency 560 THz while emitting 2.7 × 1041 photons per second.
Part (a) If 80% of the emitted photons reach the sail and are absorbed by it, find the resulting force, in newtons, on a sail that is momentarily at rest with respect to the laser.
Part (b) Now assume the photons are reflected by the sail. Keeping all the other assumptions of part (a), find the force the light beam exerts on the sail, in newtons.
Part (c) Ideally it would be best to use photons provided by natural sources to push the sail. If a star emits ns photons per second uniformly in all directions, with all the photons of frequency fs, enter an expression for the force on the sail if all the photons that strike it are reflected. Assume that the sail has an area A, is located at a distance d from the star’s center, is perpendicular to the incoming photons, and is momentarily at rest with respect to the star. Form your expression in terms of the defined quantities, h (Planck’s constant), and c (the
Part (d) Find the force, in newtons, acting on the starlight driven sail, using the following data for the star and the sail:
ns = 1.9 × 1065 photons per second
fs = 520 THz
A = 207.4 m2
d = 17 × 1011 m
Please answer all parts of the problem. Thank you so much!
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