Lasers and velocities Lasers are used to accurately measure velocities of objects. Laser l...

Lasers and velocities Lasers are used to accurately measure velocities of objects. Laser light produces an oscillating electromagnetic field E with a constant frequency f that can be described by

If a laser beam is pointed at an object moving toward the laser, light will be reflected toward the laser at a slightly higher frequency, in much the same way as a train whistle sounds higher when it is moving toward you. If Δf is this change in frequency and v is the object’s velocity, then the equation

can be used to determine v, where c = 186,000 mi/sec is the velocity of the light. Approximate the velocity v of an object if Δf = 108 and f = 1014.