SCI206 midterm 2 study cards || GUARANTEED PASS!!
Electric charges create a (monopole) electric field.
Magnets make magnetic fields (dipole)
Electric current makes a magnetic field
Changing magnetic field make electric fields
Changing electric fields make a magnetic field correct answers True?
How do radio antenna work? correct answers Charges move up and down the antenna at a set
frequency to make an electromagnetic wave.
The electromagnetic field is polarized;
-the electric field runs parallel to the antenna
-the magnetic field runs perpendicular to antenna
Electromagnetic Waves can travel through anything, including vacuums at the speed of light
correct answers True
What is the optimal length of an antenna? correct answers 1/4 of the length of the wavelength of
the electromagnetic wave running through it
Inductor correct answers A coil that generates a magnetic field
Capacitor correct answers An electrical device used to store electrical charge or electrical energy
How do radio transmitters work correct answers Transmitters work if the tank circuit frequency
matches the sending frequency
How do microphones work correct answers Microphones have a vibrating membrane around a
coil with a magnet in the middle.
As you talk, the sound waves cause the membrane to vibrate, causing the coil to move and
generating an electromagnetic wave
AM Radio (Amplitude Modulation) correct answers Weaker/Quieter sound => lower amplitude
of AM radio wave; AM amplitude needs to match the amplitude of the sound wave
=> results in quieter sounds being less clear, and louder sounds more clear
-very long antennas (~75m)
-smaller bandwidth range, lower frequency
, -can be picked up farther away; bounces off things
-picks up magnetic field, but not the electric wave
-rotation of the radio changes the volume of the sound
Carrier Frequency correct answers The frequency of the antenna of a radio station
FM Radio (Frequency modulation) correct answers Change frequency of radio wave based on
how loud or quiet the sound is
-larger bandwidth range, higher frequency
quiet sounds and loud sounds are equally clear (amplitude of sound doesn't matter) as the radio
waves are always sent at max amplitude
-line of sight radius; easily blocked by Earth's curvature; cuts off when distance is too far
How does a tank circuit work? correct answers A tank circuit has an inductor (generates a
magnetic field) and a capacitor (stores electric energy)
Alternates between electric and magnetic fields
How does a cathode ray tube work? correct answers An electron beam coming from the cathode
is steered through the tube and hits different parts of the phosphor coating (screen), causing the
screen to light up
What is the speed of light? correct answers 3.00 x 10^8 m/s in a vacuum. However the speed of
light is slower in other mediums (i.e. glass)
How does a microwave work? correct answers Polar molecules orient themselves so that their
positive and negative dipoles line up along an electric field
Microwaves generate electromagnetic waves, creating an alternating electric field, which makes
water molecules (or any polar, mobile molecule) rotate/oscillate, generating heat
This is the reason microwaves cannot work well with nonpolar molecules and frozen food (not
mobile)
What powers a microwave? correct answers A microwave contains a tank circuit resonator with
a small 3/4 coil that generates a magnetic field.
In microwaves, a tank circuit is powered by a magnetron.
Magnetron correct answers A structure of 8 tank circuits with current running through it. A wire
goes down the center of the circuits and a large negative voltage is run through the wire.
Electric charges create a (monopole) electric field.
Magnets make magnetic fields (dipole)
Electric current makes a magnetic field
Changing magnetic field make electric fields
Changing electric fields make a magnetic field correct answers True?
How do radio antenna work? correct answers Charges move up and down the antenna at a set
frequency to make an electromagnetic wave.
The electromagnetic field is polarized;
-the electric field runs parallel to the antenna
-the magnetic field runs perpendicular to antenna
Electromagnetic Waves can travel through anything, including vacuums at the speed of light
correct answers True
What is the optimal length of an antenna? correct answers 1/4 of the length of the wavelength of
the electromagnetic wave running through it
Inductor correct answers A coil that generates a magnetic field
Capacitor correct answers An electrical device used to store electrical charge or electrical energy
How do radio transmitters work correct answers Transmitters work if the tank circuit frequency
matches the sending frequency
How do microphones work correct answers Microphones have a vibrating membrane around a
coil with a magnet in the middle.
As you talk, the sound waves cause the membrane to vibrate, causing the coil to move and
generating an electromagnetic wave
AM Radio (Amplitude Modulation) correct answers Weaker/Quieter sound => lower amplitude
of AM radio wave; AM amplitude needs to match the amplitude of the sound wave
=> results in quieter sounds being less clear, and louder sounds more clear
-very long antennas (~75m)
-smaller bandwidth range, lower frequency
, -can be picked up farther away; bounces off things
-picks up magnetic field, but not the electric wave
-rotation of the radio changes the volume of the sound
Carrier Frequency correct answers The frequency of the antenna of a radio station
FM Radio (Frequency modulation) correct answers Change frequency of radio wave based on
how loud or quiet the sound is
-larger bandwidth range, higher frequency
quiet sounds and loud sounds are equally clear (amplitude of sound doesn't matter) as the radio
waves are always sent at max amplitude
-line of sight radius; easily blocked by Earth's curvature; cuts off when distance is too far
How does a tank circuit work? correct answers A tank circuit has an inductor (generates a
magnetic field) and a capacitor (stores electric energy)
Alternates between electric and magnetic fields
How does a cathode ray tube work? correct answers An electron beam coming from the cathode
is steered through the tube and hits different parts of the phosphor coating (screen), causing the
screen to light up
What is the speed of light? correct answers 3.00 x 10^8 m/s in a vacuum. However the speed of
light is slower in other mediums (i.e. glass)
How does a microwave work? correct answers Polar molecules orient themselves so that their
positive and negative dipoles line up along an electric field
Microwaves generate electromagnetic waves, creating an alternating electric field, which makes
water molecules (or any polar, mobile molecule) rotate/oscillate, generating heat
This is the reason microwaves cannot work well with nonpolar molecules and frozen food (not
mobile)
What powers a microwave? correct answers A microwave contains a tank circuit resonator with
a small 3/4 coil that generates a magnetic field.
In microwaves, a tank circuit is powered by a magnetron.
Magnetron correct answers A structure of 8 tank circuits with current running through it. A wire
goes down the center of the circuits and a large negative voltage is run through the wire.
