SAT II Physics : Optics, Waves, and Quantum
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Example Questions
Example Question #1 : Frequency And Period
What is the wavelength of a 
The relationship between wavelength and velocity is given by the equation;
The question gives us the velocity of the wave and its frequency. Using these values, we can solve for the wavelength.
Example Question #1 : Velocity, Frequency, And Wavelength
What best describes how a wave is affected when it travels from one medium to another medium?
The frequency changes, but the speed remains the same
Both speed and frequency change
The wave speed changed, but the frequency remains the same
Neither speed not frequency change
The wavelength does not change
The wave speed changed, but the frequency remains the same
It is a property of waves that the frequency remains constant and speed changes as it passes from one medium to another.
Example Question #1 : Doppler Effect
A train blows its whistle as it approaches a station at 
Wave frequency is distorted when the observer or source is in motion based on the Doppler effect. The equation for the Doppler effect is:
Terms in the numerator are summed if the observer moves toward the source. Terms in the denominator are summed if the source is moving away from the observer.
In this question, the train (source) is moving toward the observer. This means that the denominator terms will be subtracted. The velocity of the observer is zero, giving us our final equation:
Use the given values for the emitted frequency, velocity of the train, and speed of sound to solve this equation.
Example Question #2 : Doppler Effect
A dog is stationary in someone's front yard and barks at a frequency of 
The observer is moving away from the dog
The observer is traveling in circular path with the dog at the center of the circle
Both the dog and the observer have the same acceleration
The observer is moving towards the dog
Both the dog and the observer have the same velocity
The observer is moving towards the dog
The doppler effect states that the observed frequency depends on the frequency produced, and the relative velocities of the observer and sound source:
To increase the observed frequency the sound source and the observer must be moving towards each other. Since the dog is stationary, therefore the observer must be moving towards the dog.
Example Question #4 : Optics, Waves, And Quantum
Light passes from a medium with some index of refraction 
Snell's law states:
If we substitute the values from the question we get:
Next rearrange to isolate
Example Question #1 : Optics, Waves, And Quantum
Which of the following scenarios would result in the polarization of light?
Light is absorbed by a black body
Light passes through a vacuum
A light source travels at a high velocity
Light is reflected off of a glass window
Light pass between two mediums with the same index of refraction
Light is reflected off of a glass window
Light is polarized when it is all oscillating in the same direction. This effect occurs when light is reflected. Polarization can occur through refraction, however if light is passing between mediums with the same index of refraction, the light will not refract.
Example Question #2 : Optics, Waves, And Quantum
Of the following, which type of waves has the longest wavelength?
X-rays
Gamma rays
Green light
Orange light
Microwaves
Microwaves
Wavelength and frequency have an inverse relationship; as one value increases, the other value decreases. In contrast, frequency and wave energy have a direct relationship; as one term increases, the other increases as well.
In the electromagnetic spectrum all wave types have the same velocity, but some have greater energy (and frequency) than others. Gamma rays have the highest energy, while radio waves have the lowest. In order from lowest energy to highest, the types of electromagnetic waves are radio waves, microwaves, infrared light, visible light, ultraviolet light, X-rays, and gamma rays.
Of the given answer options, microwaves have the lowest energy. This means they will also have the lowest frequency, and largest wavelength.
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