Unit 2 Electromagnetism, circuit. Done no need for Coulomb's law, lithium-ion battery Flashcards
What are magnets and what are their types? what type of force is magnetic force?
A magnet is a material that produces a magnetic field. (Magnetic force is a non-contact force).
Magnets are 2 types artificial and natural.
Artificial magnets can either be permanent which means they retain their magnetism without any external magnetic field
or temporary which means they can’t retain their magnetism for more than an hour.
Is a magnetic field force constant all around the field?
A magnetic field is like a router the force will get stronger the closer you get to the magnet (router).
What is the strongest natural magnet?
Lodestone is the strongest natural magnet.
Moreover the first discovered natural magnet.
What is the Earth’s magnetic feild? and why is it important? Does it change?
A magnetic field that starts in the core of the earth, getting out into space forming a magnetosphere.
This happens because of the motion of molten iron and nickel found in the earths outer core.
The magnetic field protects the earth from solar wind and many more things. The direction and strength of the Earth’s magnetic field change over time.
What is the difference btw the magnetic poles, geomagnetic poles, and geographic poles?
Magnetic poles are the points on the Earth’s surface where the magnetic field lines are vertical, pointing directly into or out of the Earth. 2 N-S.
(the poles change place and even flip orientation from time to time. the last time was 700 000 years ago)
Geomagnetic poles are the points on the earth’s surface where the magnetic field intersects the earth’s surface. 2 North-South
Geographic poles are the points on the earth’s surface where its axis of rotation intercepts with its surface.
2 N-S
What is the difference btw an electric charge and an electric field?
Electric charge is a fundamental property of matter that gives rise to electric forces. Its unit is. coulomb and it can be positive or negative.
Conservation of charge: Charge can neither be created nor destroyed.
An Electric Field is a region around a charged particle where the charge can affect other particles/objects
What is static electricity? and what are conductors and insulators?
Imbalance between the number of electrons and protons in an object leading to either positive or negative charge.
Conductors: a substance that can easily transfer electric charge
Insulators: a substance that can’t transfer electric charge,
What are electron charging methods?
1) By friction or tribo electric effect: The movement of electrons when rubbing 2 objects together.
2) By contact/conduction: The transfer of electrons when 2 objects touch each other.
one becomes positive and one becomes negative depending on their properties in both first.
3) By induction: charging an object without actually touching the object with any other charged material. like grounding.
What is Coulomb’s law?
It is the formula used to know the force between 2 objects.
F=Kq1q2/d^2
where q is the magnitude of the charge, d is the distance btw the 2 objects
,and K is coulomb’s constant= 910^9Nm^2/C^2
What is polarization
The temporary alignment of the electrons and protons each on one side of the object due to the force of another electric field. Not charging.
what is oxidation and reduction in batteries?
Oxidation: The loss of e- from a substance to another during a chemical reaction. makes free electrons to move through the circuit.
Reduction: The gain of e- from a substance during a chemical reaction. Accepting the free electrons that came from the circuit.
What is the journey of electrons in a circuit lighting a filament lamp?
The electrons are in the cathode with charge because of oxidation. When a lamp is connected with wires to the cathode and the anode of the battery electrons move through the wire from cathode to anode because negative charge gets attracted to positive charge.
On their way, electrons pass through the lamp filament facing resistance and transforming kinetic energy into heat energy producing light.
Then the electrons go to the anode and are gained by a process called reduction.
This process keeps happening until the battery dies.
How does a lithium-ion battery work?
In lithium Ion batteries the anode is made up of graphite which acts as the storage and attracts electrons as it is positive.
The cathode is made up of lithium metal (like cobalt) oxide.
The electrolyte is a lithium salt dissolved in a solvent. It acts like a gourd that only allows lithium ions to get in.
During charging: Lithium electrons in the lithium metal oxide get free because of oxidation, they will get attracted to the positive side of the battery so they go there. the lithium ions will get attracted to the new negative side so they will go through the electrolyte to the graphite.
During discharging: Lithium electrons will go back to the cathode powering the electrical device and then the lithium ions will go through the electrolyte again bonding with the metal oxide.
What is Current
the amount of charge passing through a wire over a period of time. Ohm’s law states that current(I)=Voltage(V)/Resistance(R)
Current is constant in series circuits but not in parallel circuits and the equation:
current1+ current2 … =current total
(some math stuff in in the exam: This is because voltage is directly proportional and resistance is inversely proportional (I∝1/R) to Current. any 2 directly and inversely proportional will make this equation x=directly proportional/inversely proportional
If two variables x, y are inversely proportional, then x ∝ 1/y, that means xy = k (some constant), and if they are directly proportional, then x ∝ y that means x/y = k)
Parallel and series circuits
Series: All circuit elements are arranged in a single path
Parallel: A circuit with more than one path
