| How is magnetism linked to electricity? | Magnetic Fields affect the motion of charges, charges in motion produce magnetic fields, and changing magnetic fields can create electric fields. |
| Poles: | Located at the ends of the object (N and S) where the objects are most attracted. Like poles attract each other and unlike repeal each other. But cannot be isolated, in charges yes. When you break a magnet you would have a south and a north. |
| How can an unmagnetized piece of iron can be magnetized? | Stroking it with a magnet, like an uncharged object is charged by conduction. Because magnetism can be inducted. |
| Difference between soft and hard magnetic materials: | Soft are easily magnetized, but lose their magnetism easily and Hard are diff. to magnetize and lose their magnetism. |
| Sources of Magnetic Fields: | Region surrounding a moving charge (includes a magnetic & electric field) & a magnetized magnetic material. |
| Properties of Magnetic Fields: | 1° Vector quantity.
2° Symbol: B.
3° Directed to the north.
4° Magnetic field lines show how the field would look like (direction, loops) |
| Dif. between the magnetic and electric field lines? | Magnetic are close loops trying to reach each other and electrical dipole are forming open loops. |
| Earth Margnetic Field. | The north is the south, the south is the north. |
| What happen when a charged particle is moving through a magnetic field? | A magnetic force acts on it (Loren's force), with a max when the particle moves perpendicular to the magnetic field lines and 0 when moves parallel to the field lines. |
| How to calc. the magnitude of the magnetic force? | B=F/(q v sin(theta))
theta is the angle between the v and B |
| Magnetic field unit: | The tesla(T) or Wb/m^2 or 10^4gauss=1T |
| Right hand rule to the magnetic field. | F is perpendicular to both V and B. Use the right hand to positive charge and left to negative charges. |
| Why do we have a force on a Current Carrying Conductor(wire)? | The current is a collection of many charged particles in motion, creating a magnetic field. The direction of the force given by the right-hand rule. The magnetic force is exerted on each moving charge. |
| The total magnetic force on a current-carrign conductor? | Sum of all the magnetic forces on every charge producing the current. F= B q (length) sin(theta) |
| Rules of a Torque on a current loop: | T= B I A N sin(theta)
theta= angle between IAN and B. With a max when theta=90° & 0 when theta=0/parallel to the plane of the loop.
- Any shape of loop. |
| Solenoid | Conductor that is on loops. |
| Magnetic moment: | Mue= IAN
- The vector points perpendicular to the loop's plain.
SO... T= mue B sin (theta) |
| How DC electric motor works? | W/ a single loop connected to the power of the direct current, connect to brushes to change the direction of the current giving the loop the force to keep rotating. The loop is inside of a magnet (electro motive force or a magnetic field). As the loop becomes perpendicular to the magnetic field and the T=0, inertia carries the loop forward and the brushes cross the gaps in the ring= current reverse direction. |
| How AC electric motor works? | Revelsal of the current ocures naturally. |
| What is the direction of a Charged particle in a magnetic field with a velocity perpendicular to the field and a force directed to the center of the circular path? | The magnetic force= centripetal acceleration, changing the direction of the velocity of the particle. F= q v B= (mv^2)/ r |
| How was the electron discover/proved? | Cyclotron equation:
r=mv/qB |
| What happen if the particle's velocity isn't perpendicular to the field? | The path is a spiral. |
| Julie effect? | A current will start going in the filament and because of the dissipation of the energy/resistance= light. |
| Right Hand Rule for the direction of the Field of a long Straight wire. | Point the thumb in the direction of the current and curl the fingers in the direction of the field. |
| How to calc. the magnitude of the field, of the distance r from the wire carrying a current I : | B= (mue)I/2(pie)r
mue=4(pie)x10^-7 Tm/A
- In a close circular path. |
| What is mue? | The permittivity of free space. |
| Ampère's Circular Law | (sigma BII)(dif L)= (mue) I
Bll (sigma dif L)= (mue) I
- sigma dif L= Arbitrary perimeter of the close path |
| How can you obtain the Force Between 2 Parallel Conductors? | The force on wire 1 is due to the I in wire 1 and the B by wire 2.
F/L= ((mue)I1 I2)/2 pie d |
| How could you obtain the field B2 at wire 1? | F1= (B2) L (I1) |
| Is the F attractive or repulsive when 2 parallel wires have their I in oposite directions? | The F is repulsive, and attractive when the wires have same direction. |
| How can you enhance the strength of a B? | Forming a wire into a loop, with a B at the center pointing up/down and at the sides perfect circles. Resembling the field lines of a magnet bar. |
| How do you calc. the Magnetic fields of a Current Loop? | B= mue I/2R- at the center of the loop
B=N mue I/2R- at the loop |
| Solenoid? | It's a wire bend as a coil/ electromagnet because it carries a current. |
| How do you calc. the Magnetic fields inside a solenoid? | B= mue n I
n= N/L |
| How do we assume happen to the solenoid B? | Inside is uniform and outside is 0. |
