Pat\'s engine works by shining two lasers onto either side of his ship. The lase
ID: 1390359 • Letter: P
Question
Pat's engine works by shining two lasers onto either side of his ship. The laser coming from the left has a power of 100 mW, distributed over an area of 1.0 cm2. The laser coming from the right is made up of light with a wavelength lambda = 400 nm. How many photons per second must hit the object from the beam from the right to keep the ship static equilibrium? If the beam from the right is also over an area of 1.0 cm2, what is its intensity? If Pat changed his ship such that the beam from the left was reflected instead of absorbe be the net force on the ship?Explanation / Answer
Here ,
a)
energy of 1 photon , E = h*3*10^8/wavelength
E = h * 3 *10^8 /400 *10^-9
E = 4.97 *10^-19 J
Number of photons per second = 100 *10^-3 /4.97 *10^-19
Number of photons per second = 2.012 *10^17
b)
Intensity , If = power/area
If = 100 *10^-3 /1 *10^-4
If = 1000 W/m^2