Podcast
Questions and Answers
What is the highest point of a wave called?
What is the highest point of a wave called?
- Wavelength
- Trough
- Amplitude
- Crest (correct)
Higher frequency waves have a longer wavelength.
Higher frequency waves have a longer wavelength.
False (B)
What is meant by the term 'amplitude' in relation to waves?
What is meant by the term 'amplitude' in relation to waves?
Amplitude is a measure of the energy a wave carries.
One hertz equals one ______ per second.
One hertz equals one ______ per second.
Match the following terms with their definitions:
Match the following terms with their definitions:
What type of wave property is measured between two successive wave crests?
What type of wave property is measured between two successive wave crests?
The midpoint of a wave is used to determine its amplitude.
The midpoint of a wave is used to determine its amplitude.
What happens to the rope when you move your hands up and down quickly?
What happens to the rope when you move your hands up and down quickly?
How do electromagnetic waves behave when reflected?
How do electromagnetic waves behave when reflected?
Moving your hands slowly does not create any waves in the rope.
Moving your hands slowly does not create any waves in the rope.
Who discovered the deflection of a magnetic needle due to electric current?
Who discovered the deflection of a magnetic needle due to electric current?
Ampere's Law describes the mathematical relationship of the magnetic force between two __________ currents.
Ampere's Law describes the mathematical relationship of the magnetic force between two __________ currents.
Which of the following scientists is NOT mentioned as a contributor to electromagnetic theory?
Which of the following scientists is NOT mentioned as a contributor to electromagnetic theory?
Match each scientist with their contribution to electromagnetic theory:
Match each scientist with their contribution to electromagnetic theory:
What is the effect of moving your hands at different speeds when creating waves on the rope?
What is the effect of moving your hands at different speeds when creating waves on the rope?
Electromagnetic waves can be created by moving an electrically charged object back and forth.
Electromagnetic waves can be created by moving an electrically charged object back and forth.
What phenomenon involves generating an electrical current from a changing magnetic field?
What phenomenon involves generating an electrical current from a changing magnetic field?
Joseph Henry was able to support 2,063 pounds with his developed electromagnet.
Joseph Henry was able to support 2,063 pounds with his developed electromagnet.
In what year did Michael Faraday make his first discovery of electromagnetism?
In what year did Michael Faraday make his first discovery of electromagnetism?
Maxwell proposed that a changing electric field in space produces a ________ field.
Maxwell proposed that a changing electric field in space produces a ________ field.
Match the scientists with their contributions:
Match the scientists with their contributions:
What is the approximate speed of electromagnetic waves as concluded by Maxwell?
What is the approximate speed of electromagnetic waves as concluded by Maxwell?
James Clerk Maxwell believed that electromagnetic waves can exist in empty space.
James Clerk Maxwell believed that electromagnetic waves can exist in empty space.
What important principle did Joseph Henry discover related to inductance?
What important principle did Joseph Henry discover related to inductance?
As the speed decreases, if we change the medium of electromagnetic waves from air to water, the frequency:
As the speed decreases, if we change the medium of electromagnetic waves from air to water, the frequency:
Electromagnetic waves require a medium to propagate.
Electromagnetic waves require a medium to propagate.
What is the speed of an electromagnetic wave in a vacuum?
What is the speed of an electromagnetic wave in a vacuum?
Electromagnetic waves consist of changing ______ and ______ fields.
Electromagnetic waves consist of changing ______ and ______ fields.
Which of the following statements is NOT true for electromagnetic waves?
Which of the following statements is NOT true for electromagnetic waves?
How are frequency and wavelength of an electromagnetic wave related?
How are frequency and wavelength of an electromagnetic wave related?
Match the electromagnetic waves with their common usage:
Match the electromagnetic waves with their common usage:
What is the wavelength of radio waves broadcasted at a frequency of 675 kHz?
What is the wavelength of radio waves broadcasted at a frequency of 675 kHz?
All electromagnetic waves travel through a vacuum at different speeds.
All electromagnetic waves travel through a vacuum at different speeds.
What is the frequency of a wave whose wavelength is 4.10 x 10^-12 m?
What is the frequency of a wave whose wavelength is 4.10 x 10^-12 m?
What describes the relationship between the frequency and wavelength of electromagnetic waves?
What describes the relationship between the frequency and wavelength of electromagnetic waves?
An electromagnetic wave with a long wavelength has a __________ frequency.
An electromagnetic wave with a long wavelength has a __________ frequency.
How are the electric and magnetic fields of an electromagnetic wave oriented?
How are the electric and magnetic fields of an electromagnetic wave oriented?
An oscillator with a charged particle oscillating at a frequency of 300 MHz produces a wavelength of __________.
An oscillator with a charged particle oscillating at a frequency of 300 MHz produces a wavelength of __________.
Find the frequency of an electromagnetic wave with a wavelength of $2.75 imes 10^{-8}$ m.
Find the frequency of an electromagnetic wave with a wavelength of $2.75 imes 10^{-8}$ m.
Match the type of wave with its characteristic:
Match the type of wave with its characteristic:
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Study Notes
Electromagnetic Wave Theory
- Hans Christian Oersted discovered in 1820 that a magnetic needle is deflected when the current in a nearby wire varies
- André-Marie Ampere conducted experiments to understand the relationship between electric current and magnetism, formulating Ampere's Law
- Michael Faraday demonstrated electromagnetic induction in 1831, showing that a changing magnetic field can create an electric current
- Joseph Henry made improvements to electromagnets by insulating the wire, increasing the power of the magnet
- James Clerk Maxwell theorized that electromagnetic induction could occur in empty space, proposing that changing electric and magnetic fields generate and propagate each other as a form of energy, which he called electromagnetic waves
- Heinrich Hertz designed an experiment to generate and detect electromagnetic waves, confirming Maxwell's theory
Properties of Electromagnetic Waves
- Crest is the highest point of a wave, where the electromagnetic field is strongest
- Trough is the lowest point of a wave, where the electromagnetic field is weakest
- Wavelength is the distance between two identical points on consecutive waves, usually measured between crests or troughs
- Frequency is the number of wavelengths that pass by a point in a given time, measured in Hertz (Hz), where 1 Hz equals one cycle per second
- Amplitude is a measure of the energy a wave carries, determined by the distance from the midpoint to a crest or trough
- Electromagnetic waves travel at a constant speed in a given medium, with a speed of c = 3.0 x 108 m/s in a vacuum
- Electromagnetic waves are disturbances in a field, not a medium
- Electromagnetic waves consist of electric and magnetic fields that are perpendicular to each other
- Electromagnetic waves are formed when moving charged particles transfer energy through a field
Relationship between frequency and wavelength
- Higher frequency causes shorter wavelength and greater energy
Propagation of Electromagnetic Waves
- Electromagnetic waves are propagated as moving charged particles transfer energy through a field, creating disturbances in the electric and magnetic fields.
Frequency vs. Wavelength
- A wave with a low frequency will have a long wavelength and relatively low energy.
- A wave with a high frequency will have a short wavelength and relatively high energy.
Speed of electromagnetic waves
- The speed of an electromagnetic wave in a vacuum is constant at 3.00 x 108 m/s.
Other Key Facts
- Electromagnetic waves can be reflected.
- Electromagnetic waves can travel through a vacuum.
- Electromagnetic waves transport energy.
- The electric and magnetic fields of an electromagnetic wave are perpendicular to each other.
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