Doppler effect Definition and 486 Threads

"Basic" problem regarding doppler effect of light (E/M waves) 1. At what speed would one have to move at to see a red light as green. Presume red light wavelength = 630nm and green light wavelength = 530nm. 2. f0=fs√([1+v/c]/[1-v/c]) >f0 = observed frequency >fs = source frequency >v...

what does the doppler effect mean for an individual photon? for instance in a blue shift do the photons actually have more energy if they were originally a lower frequency?

I remember reading in a book that if we approached a red light really fast it would appear green to us due to the Doppler effect of light does anyone know how fast we would need to travel for this to happen.

Homework Statement A car is driving down the road at 25m/s. Inside the car, the radio is blaring music at 1800Hz. How would it sound to a person standing still a) in front of the car b) behind the car?Homework Equations [fo/(vw+vo)] = [fs/(vw-vs)]The Attempt at a Solution a) [fo/(vw+vo)] =...

Homework Statement A radar beam has a wavelength of .02 m. The frequency is 17500 Hz. What would be its echo frequency if a rocket 60km away is moving at 500m/s and the radar is coming from a jet moving at 310m/s towards the rocket which is aimed at it? (b) Would the rocket appear red shifted...

Homework Statement A train approaches, and passes through, a station. During this period the velocity of the train is constant and the engine is continuously sounding its whistle. Which one of the following correctly describes what an oberver on the platform will hear? Sound heard as...

Homework Statement An ambulance with a siren emitting a whine at 1530 Hz overtakes and passes a cyclist pedaling a bike at 2.22 m/s. After being passed, the cyclist hears a frequency of 1519 Hz. How fast is the ambulance moving? (Take the speed of sound in air to be 343 m/s.) Homework...

Homework Statement Hearing the siren of an approaching fire truck, you pull over to the side of the road and stop. As the truck approaches, you hear a tone of 470 Hz; as the truck recedes, you hear a tone of 400 Hz. How much time will it take the truck to get to the fire 2.5 km away assuming...

Homework Statement A car moving at 35 m/s approaches a stationary whistle that emits a 220 Hz sound. The speed of sound is 343 m/s. What is the speed of sound relative to the driver of the car? Homework Equations fo = fs [1 +/- vo/v] / [1 +/- vs/v] The Attempt at a Solution Dont...

Homework Statement Horseshoe bats use the Doppler Effect to determine their location. A horseshoe bat flies toward a wall at a speed of 15 m/s while emitting a sound of frequency 35 kHz. What is the beat frequency between the emission frequency and the echo? Assume that the air temperature is...

hi friends which is nice book for explanation of doppler effect please help me

I recall being taught that electrons in various "orbitals" or "energy states" absorb and emit photons of a specific frequency. I also learned that relative speed changes the observed wavelength of photons, due to the Doppler Effect. So, how is it that some electron can "absorb" a photon of a...

At a distance of 20m from a source of sound, the sound level is 40dB. If the observer backs up to a distance of 40m from the source, what will the sound level be? Basically, I said that the sound level halved = 20dB. Correct?

You are standing on railroad tracks as a train approaches at a constant velocity. Suddenly the engineer sees you, applies the brakes, and sounds the whistle. What do you hear starting at that moment? Because the waves are "stretching" as it approaches you slower and slower, I said that the...

Homework Statement Ok here's the problem.. a little lengthy so bear with me :) (3 parts need help w/ last two) Expectant parents are thrilled to hear their unborn baby's heartbeat, revealed by an ultrasonic motion detector. Suppose the fetus's ventricular wall moves in simple harmonic...

Homework Statement A Doppler blood flow unit emits ultrasound at 5.0 {\rm MHz}. What is the frequency shift of the ultrasound reflected from blood moving in an artery at a speed of 0.20 m/s? What equations would I use to calculate the doppler shift? It is not in my textbook...

I know which equations to use for solving Doppler Effect problems, so figuring out which is the observer and which is the source and which is moving or stationary is not the problem, the problem I am having is in solving the actual formulas... This question might belong in the math help section...

1. http://www.prep101.com/MCAT/102MCATPhysicsAnswers.pdf number 15 2. As you can see I already have the answers, I think I'm just doing something wrong. 3. I already know that the answer will be 'away' making it either a or c. So first I plugged the equation given (f1 =...

Homework Statement The security alarm on a parked car goes off and produces a frequency of 735 Hz. The speed of sound is 343 m/s. As you drive toward this parked car, pass it, and drive away, you observe the frequency to change by 78.4 Hz. At what speed are you driving? 2. The attempt at...

Homework Statement Suppose a heart's ventricular wall moves in simple harmonic motion with amplitude 1.8mm and a frequency of 115 per minute. (a) Given a motion detector in contact with the chest produces sound at 2,000,000Hz which travels through tissue at 1.50 km/s. Find the maximum linear...

John is listening to a horn. He knows the frequency of the horn is 300 Hz when both he and the horn are at rest. If he hears a pitch of 330 Hz, there are clearly several possibilities. (Give ALL correct answers, i.e., B, AC, BCD...) A) Both can be moving and have the same speed. B) Both can...

I do not fully understand the Doppler effect in light. A theoretical question: If I was traveling near the speed of light, towards a source of light. Would all the wavelengths in the visible spectrum be shortened and therefor, everything shifting towards red? I thought the speed of...

Homework Statement Do not attempt to do this experiment! You are sitting on railroad tracks, and extremely fast trains are approaching from both the left and the right. These trains have equal speeds, and both send out a warning signal with their horns. You hear this signal at a frequency...

Homework Statement Two adjacent sources each emit frequency 800 hz in air (340 m/s). how far would source 1 have to be moved so an observer in front of the sources would hear no sound? .321 .213 .123 or .312. Homework Equations f' = f/(1+ vsource/vsnd) The Attempt at a Solution i...

Homework Statement Hydrogen's only visible spectral lines are 656, 486, 434, and 410 nm. If spectral lines were of absolutely precise wavelength, they would be very difficult to discern. Fortunately, two factors broaden them: the uncertainty principle and the doppler broadening. Atoms in...

Homework Statement Assuming the speed of sound is 338 m/s: A bat moving at 6.2 m/s is chasing a flying insect. The bat emits a 53 KHz chirp and receives an echo at 53.6 KHz. At what speed is the bat catching up on its prey? Homework Equations f^{'}=[ (V_{Air} + V_{observer}) /...

Homework Statement Speed of sound in air is 340m/s. Sound from a jet, moving a 100m/s through the air, will have a speed of: Homework Equations Doppler effect, and v = Sqrt(bulk/density) The Attempt at a Solution The answer for this is 340m/s. I was wondering why. Because all the...

Homework Statement A source of sound mvoes along one straight line between listeners Abigail and Bertha. The wavelength of the sound waves heard by Abigail is about 1/2 the wavelength heard by Bertha. What is the ratio of of the speed of the source to the speed of sound? Assume that the air...

Homework Statement The calibration for a piece of ultrasound equipment states that the velocity of blood flow in the aorta is normally about 0.28 m/s, and that the detector emits a frequency of 4.20 MHz. a) If the ultrasound waves were directed along the blood flow and reflected from the...

Homework Statement A source of 1-kilohertz sound is moving straight toward you at a speed .9 times the speed of sound. The frequency you receive is: Homework Equations \nu = \frac{v}{\lambda} f' = \frac{v + v'}{v} f The Attempt at a Solution When I attempt the...

[SOLVED] Doppler Effect? Homework Statement A bat flying at 4.0 m/s emits a chirp at 20 kHz. If this sound pulse is reflected by a wall, what is the frequency of the echo received by the bat? Homework Equations Not sure. Do I use the f(1)=f*[(v+/-observer velocity)/(v+/-source...

I'm trying to detect a remote moving target. I know that if I send out a light beam against a distant target that is moving towards or away from me that the reflected light will be frequency shifted by a small amount. Now what if I amplitude modulated the light with an audio frequency. Would...

[SOLVED] Relativistic Doppler Effect and a Baseball Homework Statement A baseball coach uses a radar device to measure the speed of an approaching pitched baseball. This device sends out electromagnetic waves with frequency f_0 and then measures the shift in frequency \Delta f of the...

When a police car passes you with a siren with a frequency of 440 Hz, a noticeable drop in the pitch of the sound of the siren will be observed as the car passes by. But why the pitch suddenly drops when the car is passes by? I am not pretty sure why I heard the pitch suddenly drops, but I...

Homework Statement A speeder is pulling directly AWAY and INCREASING his distance from a police car that is moving at 27 m/s with respect to the ground. The radar gun in the police car emits an electromagnetic wave with a frequency of 7.2 x 109 Hz. The wave reflects from the speeder's car and...

[SOLVED] Doppler Effect Problem Homework Statement A submarine (sub 1) travels through water at a speed of 8.00 m/s, emitting a sonar wave at a frequency of 1400 Hz. The speed of sound in the water is 1533 m/s. A second submarine (sub 2) is located such that both submarines are traveling...

A whistle of frequency 577 Hz moves in a circle of radius 73.2 cm at an angular speed of 16.1 rad/s. What are (a) the lowest and (b) the highest frequencies heard by a listener a long distance away, at rest with respect to the center of the circle? (Take the speed of sound in air to be 343 m/s.)...

Homework Statement Assume: Take the speed of sound in air to be 341 m/s. A bat, moving at 6.3 m/s, is chasing a flying insect. The bat emits a 47 kHz chirp and receives back an echo at 47.73kHz. At what speed is the bat gaining on its prey? Answer in units of m/s. Homework Equations...

Homework Statement A train is moving parallel and adjacent to a highway with a constant speed of 25 m/s. A car, at time t0, is 42 m behind the train, traveling in the same direction as the train at 49 m/s, and accelerating at 4 m/s^2. The train's whistle blows at a frequency of 460Hz. The...

The Doppler shift formula relates two proper time intervals measured in I and I' respectovely (tau)=D(tau)' D representing a Doppler factor that depends on the relative speed of I and I'. By definition the events involved in I and I' respectively take place at the same point in space. If the...

[SOLVED] Horsehoe Bats, Insects, Speed... and the Doppler Effect Homework Statement Horseshoe bats (genus Rhinolophus) emit sounds from their nostrils, then listen to the frequency of the sound reflected from their prey to determine the prey's speed. (The "horseshoe" that gives the bat its...

I am just beginning to learn about quantum mechanics and I have already come up with a question regarding it. I know that light is absorbed by an electron at once and I know about the doppler shift. Yet is light emitted at once, or gradually? If at once, how could the wavelength be shifted...

Homework Statement I have a problem that asks to derive the doppler effect for the two different cases of a moving observer and a moving source. Homework Equations I should get f' = f*(v +/- vo)/(v +/- vs) as my general equation, where f' is the observed frequency and f is the...

[FONT="Times New Roman"]I have a few questions concerning the Doppler Effect, I know what it is in terms of a moving object, and how speed effects fequency etc. but I'm more interested in the explantions. My actual knowledge of the two explanations is reasonably vague. The one I am interested...

I am having a friendly argument with a friend. If a light source was moving towards a colored object at high speeds in a completely dark area, would the color shift due to the Doppler effect be doubled? Possible theories are no (which we agree is wrong) Yes (which may be right) Or simply...

Homework Statement Ultrasound waves are used to measure blood-flow speeds. Suppose a device emits sound at 450 kHz, and the speed of sound in human tissue is taken to be 1540 m/s. What is the expected beat frequency if blood is flowing normally in large leg arteries at 3.0 cm/s directly away...

Homework Statement A man is traveling on a bicycle at 14 m/s along a straight road that runs parallel to some railroad tracks. He hears the whistle of a train that is behind him. The frequency emitted by the train is 840 Hz, but the frequency the man hears is 778 Hz. Take the velocity of...

Doppler Effect...Ahhhh! Homework Statement A student in a parked car honks the horn, which has a `proper' frequency of 310.00 Hz. An observer in an approaching vehicle measures the frequency of the sound to be 342 Hz. Calculate the speed of the approaching vehicle. Use 340 m/s as the speed of...

Homework Statement The pitch of the sound from a racecar engine drops the musical interval of a fourth when it passes the spectators. This means the frequency of the sound after passing is 0.75 times what it was before. How fast is the racecar moving? 1. 61 m/s 2. 49 m/s 3. 72...

suppose i am moving in a train and at the same time playing a violin .Is the dopller effect/formulae applicable for me