10 Science Flashcards
Is the push and pull of an object in a particular direction
Force
Is an object that is made of materials that create a magnetic field
Magnets
External force given of by a magnet and a area in which a magnet force can be felt
Magnet fields
External force given of by a magnet and a area in which a magnet force can be felt
Magnet fields
Is the property and interraction of magnets
Magnetism
2 types of magnets
Natural and artificial
Stone which possess the property to attract other stones are called load stone
Natural magnets
Do not need matter to transfer energry
Electromagnetic waves
Are made by vibrating electric charges and can travel through space by transfering enery between vibrating electric and magnetic fields
Electromagnetic waves
How does moving charges create magnetic fields
Any moving electric charges is surrounded by an electric field and magnetic field
Making of Electromagnetic waves
When an electric charge vibrate, the electric fields around it changes creating a changing magnetic fields
The magnetic and electric fields create each other again and again
An EM wave travels in all direction. The figure only shows a wave travelling in one direction.
Electric and magnetic fields vibrate at right angles to the direction the wave travels so it is a transverves wave
Properties of EM Waves
All matter contains charged particles that are always moving,. Therefore all objects emit EM waves
The wavelenghts become shorter as the temperature of the material increases
EM waves carry radiant energy
What is the speed of EM waves
300000 km/sec in space or vacuum
(speed of light natures limit
EM waves usually travel slowest in solid and fastest in gases
Speed of EM wave
Vacuum=?
300,000 km/sec
Speed of EM waves
Air=??
<300,000km/sec
Speed of EM wave
Water=?
226,000km/sec
Speed of EM wave
Glass=?
200,000km/sec
Speed of EM wave
Diamond=?
124,000km/sec
What is the wavelenght and frequency of an EM wave?
Wavelenght = distance from crest to crests
Frequency=number of wavelength that pass a given point in 1 sec.
As frequency increase wavelenght becomes smaller
How does a radio receives different stations?
The modified carrier wave vibrates electrons in the stations antennae creating a radio wave that travels out in all directions at the speed of light to your radio antennae
The vibrating electrons produce a changing electric current which your radio seperates the carrier wave from the signal to make the speaker vibrate creating sound waves
What is an AM radio?
In Am amplitude changes but frequency does not. AM frequency range from 540,000 Hz to 1,6000,000 Hz usually listed in kHz
What is an FM radio
In FM radio station transmit broadcast information by changing the frequency of the carrier wave. The strength of FM waves is always the same and is in megahertz
Mega=million
Uses radio waves to send electronic signals in a carier waves
Sound is sent by FM; color and brightness is sent at the same time by AM signals
Television
Sound waves - microphone - electrical signals - radio waves - transmitted to and from microwave tower - receiver - electrical signal - speaker - sound wave
Telephones
How do cordless phones work?
Cell phones and cordless telephones transceivers devices that transmits one signal and receives another radio signals from a base unit
You can talk and listen at the same time because the two signals are the different frequencies
A ____ is a small radio receiver with a phone number. A caller leaves a message at a terminal with a callback number
At the terminal the message is turned into an electronic signal transmitted by radio waves
Newer ____ can send and receive mesages
Pagers
Thousand if satellites orbit Earth. A radio or TV station sends microwave signals to the satellite which amplifies the signal and sends it back to a different place on Earth. Satellite uses different frequency to send and receive.
Communication Satellites
_______ is a system of 24 satellites, ground monitoring stations and portable receivers that determine your exact location on Earth. ______ receiver measures the time it takes for radio waves to travel from 4 different satellites to the receiver. The System is owned and operated by the US Dept of Defense, but the microwaves can be used by anyone
Global Positioning Systems
EM waves with wavelenght from about 400 billion to 10 billion of a meter.
Have enough energy to enter skin cells
Longer wavelenghts-UVA
Shorter wavelenght - UVB rays
Boyh can cause skin cancer
Ultraviolet Waves
20-50 km above earth
Molecules of 3 0 atoms
Absorb Suns harmful UV rays
Ozone layer decreasing due to CFCs in AC refrigerators and cleaning fluids
Ozone layer
Radio stations changes sound to EM waves and then your radio receiver changes the EM waves back to sound waves again
Radio Transmission
Usefulness if UV radiation
Helps body make vitamin D for healthy bones and teeth
Uses to sterilize medical supplies and equip
Detectives use fluoresent powder to find finger prints (absorb UV and glows)
EM waves with shortest wavelegth and highest frequency
High Energy - go through skin and muscle
High level exposure causes cancer
Similarities of X ray and Gamma rays
Wm with wavelenght shorter than 10 trillionths of a meter
Highest energy can travel through several centimeters of lead
Both can be used in radiation therapy to kill diseased cells
The composite image shows the all sky gamma ray backgroung
X ray and Gamma ray
Radio station change sound to EM waves back to sound waves again
Radio transmission
How does radio receive different stations
Each station broad casts at a certain frequency which you tune in by choosing their frequency
Carrier wave - the frequency of the EM wave that a station uses
Microphones convert sound waves to a changing electric current or electronic signal containing the words and music
How does a radio receive different stations?
Microphone convert sound waves to a changing electric current or electronic signak containing the words and music
The modified carrier wave vibrate electrons in the stations antennae
creating a radio wave that travels out in all directions at the speed of light to your radio antennae
