Waves and electromagnetic energy

Question 1

What is a wave?

Answer 1

It is a disturbance caused by the vibration of particles in a medium

Question 2

What is a medium?

Answer 2

It is a substance through which the wave travels. When a wave passes through a medium, the medium is only temporarily displaced. Ex: Air for sound waves

Question 3

What are the properties of waves?

Answer 3

1. Amplitude
2. Frequency
3. Time period
4. Wavelength

Question 4

Properties of waves:
What is Amplitude?

Answer 4

It is the maximum displacement of a wave on either side of its mean position. Its SI unit is Metre (m). The amplitude of a wave often determines its strength or intensity.

Question 5

Properties of waves:
What if frequency?

Answer 5

The number of cycles of a wave in 1 second or the number of vibrations per second. Its SI unit is Hertz (Hz)`

Question 6

Properties of waves:
What is the time period?

Answer 6

It is the time taken for one complete oscillation. (T) is the time it takes the object to return to its exact starting point and direction. It is measured in seconds.

Question 7

What are the types of waves?

Answer 7

1. Longitudinal waves:
   The vibration of the medium is in the same direction as the wave motion. They produce compressions and rarefactions. Ex: Sound waves
2. Transverse waves:
   The vibration of the medium is perpendicular to the direction of motion. Produce crests and troughs. Ex: Pulling a guitar string

Question 8

Properties of waves:
What is wavelength

Answer 8

It is the distance between two consecutive crests or troughs. It is measured in meters. It is denoted by Lambda (λ)

Question 9

Describe electromagnetic waves and electromagnetic radiation.

Answer 9

Electromagnetic waves are waves that consist of vibrating electric and magnetic fields. They transfer energy from one place to another.
The transfer of energy by electromagnetic waves is called electromagnetic radiation. Electromagnetic waves can transfer energy through matter or across empty space.

Question 10

Describe the electric and magnetic fields of an electromagnetic wave

Answer 10

The electric and magnetic fields of an electromagnetic wave are areas of electric or magnetic force in which their properties take place. The fields can exert force over objects at a distance.

Question 11

How does an electromagnetic wave begin?

Answer 11

An electromagnetic wave begins when an electrically charged particle vibrates. This causes a vibrating electric field which in turn creates a vibrating magnetic field. The two vibrating fields together form an electromagnetic wave.

Question 12

How does an electromagnetic wave travel?

Answer 12

An electromagnetic wave is a transverse wave that can travel across space and through matter. When it travels through space, it doesn’t lose energy to a medium, but a mechanical wave does.

Question 13

How do electromagnetic waves interact with matter?

Answer 13

When an electromagnetic wave strikes matter, it may be reflected, refracted, or diffracted. Or they may be absorbed by matter and converted to other forms of energy.

Question 14

What are the sources of electromagnetic waves?

Answer 14

The most important source of electromagnetic waves is the sun. Many other sources of electron magnetic waves depend on technology.

Question 15

What are the properties of electromagnetic waves?

Answer 15

1. All electromagnetic waves travel across space at the speed of light, which is 3*10^8 m/s
2. Electromagnetic waves may vary in wavelength and frequency. Longer wavelength electromagnetic waves have lower frequencies and vice versa.
3. The energy of an electromagnetic wave depends on its frequency.

Question 16

Relationship between speed, wavelength, and frequency:
Speed formula

Answer 16

Speed = Wavelength * Frequency.

Question 17

Relationship between speed, wavelength and frequency:
Wavelength formula?

Answer 17

Wavelength = Speed/frequency

Question 18

Relationship between speed, wavelength and frequency:
Frequency formula

Answer 18

Frequency = Speed / Wavelength.

Question 19

What is electromagnetic spectrum?

Answer 19

Sunlight contains the complete range of wavelengths on electromagnetic waves, which is called the electromagnetic spectrum.

Question 20

What are light waves?

Answer 20

They are electromagnetic waves that fall roughly in the middle of the electromagnetic spectrum. Light includes infrared light, visible light, and ultraviolet light.

Question 21

What is infrared light?

Answer 21

Light with the longest wavelength is called infrared light. The term infrared red means below red. Infrared light is the range of light waves that have longer wavelengths and lower frequencies. Sun gives off infrared light as do flames and living things. You can’t see the infrared light but u can feel it as heat.

Question 22

What are some of the applications of infrared lights.

Answer 22

1. Used in infrared cameras for nighttime photography.
2. For Therapeutic purposes
3. Remotes as sensors
4. Can travel in fog and mist.

Question 23

What is visible light

Answer 23

The only light that people can see is called visible light. The light consists of a very narrow range of wavelengths that falls between infrared light and ultraviolet light. Within the visible range we see light of different wavelengths as different colors of light. From red light which has the longest wavelength to violet light that has the shortest wavelength. As they are in sunlight visible light appears white.

Question 24

What is ultraviolet light?

Answer 24

Light with wavelengths shorter than visible light is called ultraviolet light. It is the range of light waves that have shorter wavelength and higher frequencies than violet light in the visible light range. It has more energy as it has a higher frequency.

Question 25

Applications of ultraviolet light

Answer 25

1. Can be used to kill bacteria in food 2. To sterilize surgical instruments 3, Rich in vitamin D that is important for skin etc.

Question 26

What is energy?

Answer 26

It is the ability to do work. Forms of energy are: 1. Chemical energy 2. Luminous energy 3. Nuclear energy 4. Radiant energy 5. Sound energy 6. Thermal energy

Question 27

What is the law of conservation of energy?

Answer 27

The law of conservation of energy states that energy can neither be created nor destroyed, only it changes from one form to another.

Question 28

Compare analog and digital signals

Answer 28

Analog signals: 1. Analog signals are continuous 2. Denoted by sine (curvy) waves. Ex: Human voices in air, record player, etc. Digital signals 1. Digital signals are discrete (binary) 2. Denoted by square (block) waves Ex: Computer, CD, DVD, MP3 etc.

Question 29

What are the advantages of analog signals?

Answer 29

Tape records have been proven to be useful. Records and record albums have an artistic value.

Question 30

Disadvantages of analog signals?

Answer 30

Tape/Record players are hard to find. A tape (audio or video) can break. Copying a tape can deteriorate its quality.

Question 31

Advantages of digital signals?

Answer 31

1. Can save more data in a smaller space 2. No degradation of data 3. Data can be shared electronically 4. Data can be stored remotley

Question 32

Disadvantages of digital signals?

Answer 32

1. Computer crash would result in loss of data 2. Software needs to be unto date 3. Data can get corrupted or hacked. 4. Technology can change making access to the data difficult

Question 32

What is sound?

Answer 32

It is a form of energy emitted by a vibrating source and transmitted by a material medium .

Question 33

What are sound waves?

Answer 33

They are waves carrying sound energy. They can be considered propagation of pressure or density variations in a medium. They are longitudinal waves.

Question 34

What is an echo?

Answer 34

It is a phenomenon of repetition of sound of a source by reflection from an obstacle after the original sound ceases off. The sensation of sound lasts in out brain for 0.1 seconds, this property is called persistence of hearing. When sound is repeatedly reflected from a number of obstacles at suitable distances, many echoes are heard one after the other.

Question 35

What are the conditions for a echo to be produced?

Answer 35

The minimum distance between the observer and the obstacle should be 17.2 meters. To hear a distant echo the interval between the original and the reflected sound should be 0.1 second. The size of the reflector must be larger than the wavelength of the incident sound.

Question 36

What is echo cardiography?

Answer 36

It is used to study the heart and its functions

Question 37

What is Sonar?

Answer 37

Sonar is sound navigation and ranging. Geologists use sound waves to identify geological features under the surface of the Earth. Waves are sent through the ground and bounce back to special devices that measure the materials under earth. It is also used to measure the depth of the sea called the Echo depth ranging.