Ch 5 Flashcards
Electricity vs gravity
Gravity
Can never be repulsive- always pulls objects together
Electricity
Can attract and repel based on charge
electricity is 30 times greater
Describe lightening
Rain/ wind cause uneven distribution of electrons in cloud= build up of negative at bottom= positive build up on earth’s surface (net positive charge)= build up creates a voltage between cloud and ground. Lightening strike is the electrical current that runs between the two when the voltage is high enough
Coulomb’s law
_ charges repel one another, and _ charges attract one another
The force between any two _ objects is proportional to the product of their _divided by the square of the _
Coulomb’s law
like charges repel one another, and unlike charges attract one another
The force between any two electrically charged objects is proportional to the product of their charges divided by the square of the distance between them
Electrical field
Every _ exerts forces (proportional to _)) on its surroundings to create an electric field
Electrical field
Every charged object exerts forces (proportional to 1/(d^2)) on its surroundings to create an electric field
William Gilbert
First _
Discovered magnetic poles= two ends north and south=_
Cut one in half= two smaller _
Learned
Magnetize iron and steel by rubbing with _
Hammering iron makes it _
Irons magnetism can be destroyed through _
William Gilbert
First magnet studies
Discovered magnetic poles= two ends north and south= dipole magnet
Cut one in half= two smaller magnetic dipoles
Learned
Magnetize iron and steel by rubbing with lodestone
Hammering iron makes it magnetic
Irons magnetism can be destroyed through heating
Like magnetic poles repel and opposite poles attract (forces)
describe aurora
Charged particles interacting with earths magnetic field
At poles
The convergence of magnetic field of force lines enhances the effect of visible light displays from incoming solar particles interacting with the magnetic field.
Connection between _ and _ required the invention of the battery and the electrical circuit
Connection between electricity and magnetism required the invention of the battery and the electrical circuit
Luigi and life’s electrical force
Electricity caused frogs legs to contract= _
which separates _ from _ matter
And poking with 1 iron and copper fork
Luigi and life’s electrical force
Electricity caused frogs legs to contract= animal electricity
which separates living from inanimate matter
And poking with 1 iron and copper fork
Electrical current=
Flow of charged particles- negatively charged electrons
Volta vs Luigi
explain
how both right?
Galvani’s effects were caused by chemical reactions between the metals and the salty fluids of the frogs’ legs.
Electrical charges can be induced to flow by chemical reactions
In retrospect, both of these scientists had part of the truth. Muscle contractions are indeed initiated by electrical signals and electrical charges can be induced to flow by chemical reactions
Volta invented _
Converts stored _ into _ of electrons
Volta invented battery
Converts stored chemical energy into kinetic energy of electrons
Life force present day implications
Use of magnets/ electricity to heal
Magnets can cause the_ to increase the _, which allows cells to pick up more _ and release more _
Magnets can cause the separation of blood cells to increase the available surface area, which allows cells to pick up more oxygen and release more energy
Electric circuits
_ path of material (electrical conductors) that carries _
Three parts of a circuit
- Source of energy
- Closed path through which energy can flow
- Device to use the electrical energy
Electric circuits
Unbroken path of material (electrical conductors) that carries electricity
Three parts of a circuit
- Source of energy
- Closed path through which energy can flow
- Device to use the electrical energy
OHMS law
The current in circuits is directly proportional to the _ and inversely proportional to the _. The higher the electrical “_,” the higher the flow of charge. The higher the _ to flow, the smaller the flow
Volts= current (_) x resistance (_)
The current in circuits is directly proportional to the voltage and inversely proportional to the resistance. The higher the electrical “pressure,” the higher the flow of charge. The higher the resistance to flow, the smaller the flow
Volts= current (amps) x resistance (ohms)
Current= amount of _ flowing past a point in the wire per _
1 _ of current= 1 coulomb of charge per second
Voltage= _ produced by the energy source in the circuit
Measured in _
Electrical resistance= how hard to _ electricity through wire
measured in _
The higher the resistance= more electron KE converted to _
Current= amount of electrons flowing past a point in the wire per second
1 amp of current= 1 coulomb of charge per second
Voltage= pressure produced by the energy source in the circuit
Measured in volts
Electrical resistance= how hard to push electricity through wire
Measured in Ohms
The higher the resistance= more electron KE converted to thermal E
Temperature effect
High temp= the atoms that make up the conductor start to vibrate more vigorously. As a result, mobile electrons in the conductor may collide more often with vibration atoms= increased electrical resistance*
Easier to walk through a crowd standing still vs people moving
Electric power
The power consumed by an electrical appliance is equal to the product of the _ and the _
EQT?
Electric power
The power consumed by an electrical appliance is equal to the product of the current and the voltage
P (watts)= current (amps) * voltage (volts)
P=I*V
Nerve impulse
Dendrites receive _
Axon conducts _
Myelin sheath _ axon from neighboring electrical _
Nerve impulse
Dendrites receive incoming signals
Axon conducts outgoing signals away from the nerve
Myelin sheath insulates axon from neighboring electrical interference
Oerstad exp
whenever _ flows through a wire, a _ will appear around that wire. A compass brought near the wire will twist around until it points along the direction of that _.
whenever electrical charge flows through a wire, a magnetic field will appear around that wire. A compass brought near the wire will twist around until it points along the direction of that magnetic field.
Electromagnet
A device composed of a coil of wire that produces a _ when an electrical charge runs through the wire
Electromagnet
A device composed of a coil of wire that produces a magnetic field when an electrical charge runs through the wire
The stronger the current (more electrical charge pushed through wire), the stronger the magnetic field will be
how does an electrical motor work
Electrical motor
2 permanent magnets
Rotating loop of wire between the magnets around electromagnet
Current switch on creates magnetic field and each pole is atrracted to the perm magnets.
Once aligned, the current flips to reverse the magnetic poles
The repulsive forces between like magnetic poles act to continue the rotation.
By alternating the current in the loop, a continuous rotational force is kept on the wire, and thus the wire keeps turning.
As the electromagnetic coil spins, the current flow direction is switched back and forth causing continued rotation of the coil as it responds to attraction and repulsion of N and S poles.***
Why no monopoles
If you break a magnet down to one last individual atom, you still have a dipole field because of the atomic-scale current loop. If you try to break the atom down further, the dipole field will disappear and there will be no magnetism except that associated with the particles themselves. Thus, magnetism in nature is ultimately related to the arrangement of electrical charges rather than to anything intrinsic to matter itself.
Neodymium magnet solutions (3)
Recycling
New technology that doesn’t need the magnet
New mineral
describe MRI
Motion of electrons in atoms create a current that produces a magnetic field and so does the rotation of the nucleus of the atom
Nucleus= small dipole magnet
MRI produces magnetic field that enter tissue and causes nucleus to rotate at a characteristic frequency
This effect causes the nuclei to absorb radio waves whose frequency is times to coincide with the rotation
By monitoring which radio wave frequencies are absorbed, you know tissue type (x-ray can’t)
Faraday EXP
Electrical fields and electrical currents can be produced by changing _.
EXPLAIN STORY (2)
2 coils of wire side by side with one battery connected to 1
Even though the second coil of wire was not connected to a battery, a strong electrical current developed in it.
the loop of wire through which current was running produced a magnetic field in the neighborhood of the second loop. This changing magnetic field, in turn, produced a current in the second loop by means of a process called electromagnetic induction
Moving a magnet into the region of a coil of wire causes a current to flow in the circuit, even in the absence of a battery or other source of power.
Electrical generator
Place a loop of electrical wire with no batteries or other power source between the north and south poles of a strong magnet.
From the point of view of the electrons in the wire, any rotation changes the orientation of the magnetic field. The electrons sense a changing magnetic field and hence, by Faraday’s findings, a current flows in the loop. If we spin the loop continuously, then a continuous current flows in it
Electric generator vs electric engine
Generator
Some energy turns the shaft that spins coils of wire in a magnetic field: Kinetic energy into electrical energy
Engine
Electric energy is turned into kinetic energy of spinning shaft
AC vs DC
AC eventually won because it is easier to transmit alternating current over long distances
Maxwell’s equations
_ force
A term used to refer to the unified nature of electricity and magnetism
Equations
- Coulomb’s law: like charges _, unlike _
- There are no magnetic _ in nature
- Magnetic phenomena can be produced by _
- Electrical phenomena can be produced by _
Maxwell’s equations
Electromagnetic force
A term used to refer to the unified nature of _ and _
Equations
- Coulomb’s law: like charges repel, unlike attract
- There are no magnetic monopoles in nature
- Magnetic phenomena can be produced by electrical effects
- Electrical phenomena can be produced by magnetic effects
