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Physics Midterm/quiz

physics notes

QuestionAnswer
What is the primary function of x-ray imaging systems? To convert electric energy into electromagnetic energy
Give an example of chemical energy? car battery
Give an example of electrical energy converted into mechanical energy? Electric motor
Give an example of electrical energy converted into thermal energy? A toaster
________________ are freely moveable? Electrons
Protons are more or less _________. Fixed
The total net charge of all matter in the universe is? neutral
An object is electrified when is has ________ or __________ electrons? too few/too many (has a charge)
What are the 5 laws of electrostatics? Opposites attract/likes repel, Coulomb's Law, distribution, conductor, and movement
What is Coulomb's Law? Same as the Inverse Square Law, the intensity of radiation is equal to the source squared
What is distribution with regards to the laws of electrostatics? An electrical charge is distributed uniformly throughout or on the surface
What is conductor with regards to the laws of electrostatics? An electrical charge of a conductor is concentrated along the sharpest curvature of the surface
What is movement with regards to the laws of electrostatics? Only negative charges move along solid conductors
Electrification can be created in 3 methods? Friction, contact, or induction
What is a electric ground? Neutral objects p/u excess electrons from charged object
Do positive electric charges move? No
What is a unit of electric charge? Coulomb (C)1C = 6.3 X 10 to the 18th electron charge
What is electric potential? The difference in charge between two points. It represents the amount of work done to move charge from one point to another
A unit of electric potential is measured in? Volts
Electric potential is also called? Electromotive force (EMF)
What is a conductor? Any substance through which electrons flow easilyi.e. Copper
What is an insultaor? Any material that does not allow electron flowi.e. wood, rubber
What is a semiconductor? a material that sometimes acts like an insulator and sometimes like a conductori.e. water
What is superconductivity? The property of some materials to show no resistance below a critical tempi.e. MRI
What is electricity? Electrons in motion
What is voltmeter? measures potential difference between 2 circuit points
A voltmeter is useful with a ____________ circuit? parallel circuit
What is ammeter? measures current
Ammeter is useful with a _________ circuit? series circuit
In a series circuit _____________ is constant. current
A series circuit V=IRtotal R = R1 + R2 + R3total V = V1 + V2 + V3total I = I1 = I2 + I3
In a parallel circuit ______________ is constant. voltage
A parallel circuit total V = V1 = V2 = V3total I = I1 + I2 + I3total R = 1/R1 + 1/R2 + 1/R3
What does an electric capacitor do? It stores electric charge
What is capacitance? the amount of charges that can be stored
What is a unit of capacitance? farad
Power is measured in? watts
Power formula power = current X voltageP = IVpower = I2R
Power loss increased with increased resistance? Yes
What is Lodestone? A naturally occuring magnet(first used as a compass by Chinese)
How is a magnetic field created? when a charged particle is in motion
The lines of a magnetic field are always ______ loops closed
A permanent magnet is usually made of what type of material? ferromagnetic i.e. iron
How are permanent magnets made? by aligning magnetic domains
What do electromagnets consist of? a wire wrapped around an iron core, then an electric current is conducted through the wire
How is a superconducting magnet made? when a very large current is run through many loops of wire wrapped around a very large core of ferromagnetic material and wire is immersed in a helium bath
What are diamagnetics? Materials that are weakly repelled by the magnetic field
What are ferromagnetics? materials that are very strongly attracted to the magnetic field
What is a photon? atom of lightthe smallest quantity of any type of electromagnetic radiation
What is field? interaction among different energies, forces or masses that can otherwise be described as mathematically
What is an electric field? interaction of electrostatic charges
What is a magnetic field? interaction of magnetic poles
What is amplitude? area from crest to valley on the sine wave
What is frequency? # of cycles per second
1 Hertz is equal to 1 cycle per second
What is wavelength? the distance from one crest to another (side to side)
The ___________ together the peaks, the ___________ the frequency? closer/higher
As the wavelength ___________________, the frequency ______________. decreases/increases
Wave equation: Velocity = frequency X wavelength
As the wavelength ________________, you have more crests. decreases
Frequency and wavelength are inversly proportional? True or false True
What is the difference between x-rays and gamma rays? their sources
What are the four fundamental fources of nature? Gravity, Nuclear force, weak interaction, and electromagnetic force
What did Hans Oersted do? By placing a long straight wire next to a compass, when current passed thru wire, compass point turned toward wire, creting a magnetic field. Any charge in motion creates a magnetic field
What is a solenoid? a coil of wire (used as detent locks)
What is an electromagnet? a coil of wire wrapped around an iron core, which intensifies the magnetic field
What is Faraday's Law An electric current is induced to flow in a circuit if some part of that circuit is in a changing magnetic field
The magnitude of induced current depends on the following? 1. strength of the magnetic field2. velocity of the magnetic field as it moves past the conductor3. the angle of the conductor to the magnetic field4. the number of turns in the conductor
What is Lenz's Law? The induced current flows in a direction such that it opposes the action that induced it
What are two types of induction? Self and mutual induction
What is self induction? Induction of an opposing voltage in a single coil by its own changing agnetic field
What is mutual induction? Generation of an alternating current in a secondary coil by supplying an alternating current to the primary coil
What is dipoles? groups of atoms having electrons with magnetic moments in the same direction
What laws do generators and motors use? Oersted's and Faraday's Laws
How can DC current be induced? By using a commutator ring
Electromagnetic radiation is inversly proportional to: frequency and wave length
Any charged particle in motion creates: magnetic field
The force of attraction between 2 opposite magnetic poles will be greater when poles are? closer together and magnetic field strong
The force that pushes the e- is? potential difference
The magnitude of an induced current depends on? strength and velocity of magnetic field, angle of conductor, and # of turns in conductor
What is the unit of frequency? Hertz
What is magnetic field strength measured in? tesla
The amount of voltage transmitted in a series circuit of 0.5A & 5 ohms would be? 2.5V
A series circuit has 3 resistors of 9, 10, and 16 ohms. If potential difference is 110V, what is resistance? 35 ohm
A series circuit has 3 resistors of 8, 12, & 15 ohms. If potential difference is 110V, what is total amperage? 3.14A
Created by: vahajuddin