Applied Physics - BMT 201: Introduction to Waves Lecture #1

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Questions and Answers

Which type of waves require a material medium to exist?

Sound waves

Matter waves

Electromagnetic waves

Mechanical waves (correct)

What is the speed of all electromagnetic waves when traveling through a vacuum?

$3.142 \times 10^8$ m/s

$3 \times 10^8$ m/s (correct)

$2.998 \times 10^8$ m/s

$3.5 \times 10^8$ m/s

Which type of waves are commonly used in modern technology and probably unfamiliar to most people?

Electromagnetic waves

Mechanical waves

Seismic waves

Matter waves (correct)

Which type of waves do not require a material medium to exist?

Electromagnetic waves Signup and view all the answers

Which waves are governed by Newton's laws?

Mechanical waves Signup and view all the answers

What is a common example of a matter wave according to the text?

Light wave Signup and view all the answers

What type of waves are associated with electrons, protons, atoms, and molecules?

Matter waves Signup and view all the answers

In a transverse wave, how does a typical string element move as the pulse passes?

Moves up and down continuously Signup and view all the answers

How would you describe the displacement of oscillating string elements in a transverse wave?

Perpendicular to the wave's direction of travel Signup and view all the answers

What type of wave is set up in an air-filled pipe by moving a piston back and forth?

Longitudinal wave Signup and view all the answers

Which waves are described as traveling waves in the text?

Both transverse and longitudinal waves Signup and view all the answers

What determines how fast a wave can travel on a string?

Mass and elasticity Signup and view all the answers

What is the average power of a sinusoidal wave on a stretched string dependent on?

Linear density, wave speed, angular frequency, and amplitude Signup and view all the answers

What does the principle of superposition for waves state?

The displacement of a particle is the sum of the displacements from individual waves. Signup and view all the answers

In interference of waves, what happens when two sinusoidal waves on the same string overlap?

They add or cancel out based on the principle of superposition. Signup and view all the answers

What quantities are involved in determining the speed of a wave on a string?

Tension and linear density Signup and view all the answers

What type of energy is transported by a wave as it moves along a string?

Kinetic energy and elastic potential energy Signup and view all the answers

What type of waves are governed by Newton's laws?

Transverse mechanical waves Signup and view all the answers

How are transverse mechanical waves characterized?

Particles oscillate perpendicular to the wave's direction of travel Signup and view all the answers

In describing a wave on a string, what is needed to give the shape of the wave?

A function that relates transverse displacement to time and position Signup and view all the answers

What mathematical form represents a sinusoidal wave moving in the positive direction of an x-axis?

$ym \sin(kx - \omega t)$ Signup and view all the answers

What does the frequency of a wave represent?

Number of occurrences of a repeating event per unit of time Signup and view all the answers

Which function can be used to describe a sinusoidal shape like a wave on a string?

Both sine and cosine functions Signup and view all the answers

What is the relationship between the displacement of two waves traveling alone and their displacement when they overlap?

They algebraically add to each other. Signup and view all the answers

If two identical sinusoidal waves interfere with a phase difference φ of π rad or 180°, what kind of resultant wave is produced?

A completely canceled wave Signup and view all the answers

What phase difference between two interfering waves results in a net wave that is what is actually observed on the string?

0 rad or 0° Signup and view all the answers

What effect do two sinusoidal waves of the same amplitude and wavelength traveling in the same direction have when they interfere?

They generate a resultant sinusoidal wave. Signup and view all the answers

If a string has a linear density of 0.7 kg/m and is under 80 N of tension, what is the angular frequency of a sinusoidal wave if the average power is 30W and the amplitude is 0.18 m?

$2\pi$ rad/s Signup and view all the answers

In the context of waves on a string, what happens when two waves overlap?

They produce a resultant wave. Signup and view all the answers

Study Notes

Types of Waves

Matter waves are associated with electrons, protons, and other fundamental particles, and even atoms and molecules.
Mechanical waves are common examples of waves, including water waves, sound waves, and seismic waves.
Electromagnetic waves are less familiar, but include visible and ultraviolet light, radio and television waves, microwaves, x-rays, and radar waves.
Electromagnetic waves require no material medium to exist and travel through a vacuum at the same speed c = 3x10^8 m/s.

Transverse Waves and Longitudinal Waves

A transverse wave is a wave in which the particles of the medium oscillate perpendicular to the wave's direction of travel.
A longitudinal wave is a wave in which the particles of the medium oscillate parallel to the wave's direction of travel.
Examples of transverse waves include a single pulse sent along a stretched string, and a sinusoidal wave sent along a string.
Examples of longitudinal waves include a sound wave set up in an air-filled pipe by moving a piston back and forth.

Wave Speed on a Stretched String

The speed of a wave on a string with tension τ and linear density μ is determined by the wave's velocity equation.
The velocity equation is: v = √(τ/μ)

Power of a Wave Traveling Along a String

The average power of a wave traveling along a string is: Pavg = (1/2)μvω^2y_m^2
Where: Pavg is the power (Watt), μ is the linear density (kg/m), v is the speed of the wave (m/s), ω is the angular frequency (rad/s), and y_m is the amplitude (magnitude of the maximum displacement) of the wave (m).

Interference of Waves

When two or more waves traverse the same medium, the displacement of any particle of the medium is the sum of the displacements that the individual waves would give it, an effect known as the principle of superposition for waves.
The principle of superposition states that the resultant disturbance is equal to the algebraic sum of the individual disturbances.
When two waves overlap, the displacement of the string is the algebraic sum of the individual displacements: y(x, t) = y1(x, t) + y2(x, t)
Interference can result in either constructive or destructive interference, depending on the phase difference between the two waves.

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Description

This quiz covers the basics of waves, including types of waves, wave speed on a stretched string, power of a wave traveling along a string, and interference of waves. It is based on the lecture by Dr. Suhail Alshahrani for BMT 201 at King Saud University, College of Applied Medical Sciences.