Electromagnetism IB MYP 4-5 Physics Summary Notes

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ELECTRICITY AND MAGNETISM

Charge is the tendency of atoms to attract other objects. A charge belongs to an. ion, or a charged particle. An atom gets charged by loosing or gaining electrons:
Coulombs’s law deals with the intermobular forces of attraction, and the repulsion. between objects.

$F \propto q_1 q_2$
F=Force
$q_{1}q_{2}$=charge

The more the force of attraction, the more the product of the charges.

$F \propto \frac{1}{r^2}$

$r^2 \rightarrow$ Distance

e force is inversely proportional the distance squared.

$F=\frac{K q_1 q_2}{r^2}$

k= Coulomb’s constant

coulomb’s constant is approximately $9 \times 10^9$ for air. Its the electric ce constant.
the force is increased, the rage will increase too.
; should be noted that Coulomb’ stant varies across different diums. For instance, it is lower paper.

Static electricity is the charge in stationary (resting) objects. When an objet rubs against something, due to heat, the electrons have enough energy to escape the object (abject $A$, as it can be called). The free electrons stick to another object (we can refer to it as object B). Hence, object $A$ is positive, while $B$ is negative- when they both come into contact, a spark follows, and both objects become neutral.
Electrostatic induction is the. phenomenon in which, in a presence of a charged body, the charges on the insulator lother body are distributed in asuch a way that like charges come on one side, while unlike charges come on the other end.

Electrostatic induction:

word “electrostatic” means having – with electric charges/ fields of brionary objects.

circuit is an enclosed path through electricity flows. On the other, current is the rate of flow negative/positive charges. Current easured by an ammeter in $\operatorname{eres}(A)$.

Electrons flow in a circuit that carry energy. The nucleus of an atom, inside a circuit serves no purpose. However, if it becomes unbalanced, the substance can become radioactive.
There are 2 types of circuits:
Series: Only one path in which
current electricity can flow through.
Parallel: Multiple paths.

Example of series circuit:

Series circuit, the voltage gets across different resistors, the current stays constant.
voltage is defined as the energy that is consumed. It can also be the difference between two points, or the work done or energy given to a charge in moving from a point to another against the field. Electric potential is the same. Findable using. (v)

$V_B-V_A=\frac{\text { Energy (Work Done) }}{q \rightarrow \text { charge }}$

Resistance is the opposition to the flow of charges.
should be noted that electrons are actually consumed in a series is it. The following is what actually happens:

So, over usage of a battery causes it to drain.
Current, voltage and Resistance are inter-relatable using Ohm’s law:

$I=\frac{V}{R}$

$V \rightarrow$ vollage

$C\rightarrow$ current

$R\rightarrow$ Resistance

and the equivalent resistance in a is circuit, use:

$V_{T}=R_1+R_2+R_3+\cdots$

addition, Power of a circuit can calculated using: (measured in Watts)

$V I$ or $P=\frac{V^2}{R}$ or $P=I^2 R$

transistor is the tool that provides ristance to a circuit. It basically converts electrical energy into heat energy. It divides the electric potental. circuit divider is called the initial divider.

Example of parallel circuit:

To find the equivalent resistance in a parallel circuit:

$\frac{1}{R_T}=\frac{1}{R_1}+\frac{1}{R_2}+\frac{1}{R_3}+\cdots$

Electromotive Force (EMF) is the energy that is supplied by a battery to a unit coulomb charge. It is only the energy, not actually a force.- Super conductivity is the ability of “superconductors” to conduct electricity without any resistance whatsoever. They can only, however do this in low temperatures. This is because if this is the case, then there shall be lesse kinetic energy (due to the particles having lesser energy). The other condition, apart from low temperatures, is the current being AC current (Altemating Current). Only metals can be sup erconductors, since they have a whole sea of mobile electrons. Hence they have more electronmobility. This means that the electrons are able to move about more freely.
Electromagnetic refers to an thing. that has to do with the phenomenon of the interaction of electric currents or fields and magnetic fields.
Electromagnetic Induction is the ability of a magnetic field to create current inside a conductor. A change in magnetic field causes current to be created. It causes the production of an EMF across an electric conductor in a changing magnetic field.
Magnetic flux is a measurement of the total magnetic field which passes through a given area. Faraday’s Law States that a change in magnetic flux can induce an EMF.

Faraday’s Law:

$N=\frac{\Delta \Phi}{\Delta t}$

$\Delta \Phi \rightarrow$ change im magnetic flux

$\Delta t \rightarrow$ change in time

$N \rightarrow $ induced EMF

Diagram of this process:

The electrons move back and forth. Adding the magnet sends the reading in $t$, but then retums to zero. Once pulled out, it goes into – . This is due. to the changes in magnetic flux. If the magnet is pulled back and forth the electrons will travel that way too, producing an emf. The graph of the emf will look similar to that of $y=\sin x$.
Factors affecting this process:
Strength of magnet: Higher will cause higher emf.
Number of coils. Higher will cause high her emt.
Lenz’s Law states that the direction of an induced current is always such as to oppose the changes in the circuit or the magnetic field that produces it (perpendicular to it)

Fleming’s right-hand rule confirms this:

On the principles of electromagnetic induction, electricity can be produced on very large scale. All that is needed is a huge rotor and magnet.
An AC generator is a rotor that spins and turns mechanical energy into electrical energy.