Physics - Magnetic Forces & Fields

Application of the right hand rule at any point shows that the magnetic force is always toward the ________________. The magnetic force is effectively a centripetal force that changes only the direction of the ________ and not the magnitude.

center of a circular path, velocity

A mass spectrometer is a device that uses the magnetic force on a ____________ to determine the relative mass and abundance of an isotope or to help identify unknown particles. Particles are first ionized, and then accelerated through a known potential difference into a uniform ___________ where the particle travels in a circular path until it hits a detector. By knowing the these three things the particles mass can be found.

charged particle, magnetic field field strengths, charge, and the radius of the path

The direction of the force can be found using the right hand rule. Point fingers in the direction of the magnetic field, thumb in the direction of the _______ (flow of positive charge), and your _____ will point in the direction of the force.

current, palm

What is the ultimate source of all magnetic fields?

electric current (moving charged particles)

To use the right hand rule, point _________ in direction of the magnetic field, ________ in direction of the velocity of a positive charge, and the ________of your hand will point in the direction of the force

fingers, thumb, palm

define Magnetic domains

groups of atoms that have the same magnetic dipole orientation.

The Earth's _____________ is due to the movement of charges in convection currents beneath the earth's crust.

magnetic field

Magnetic poles always occur in ______ (dipoles).

pairs

Since the magnetic force is perpendicular to the magnetic field, but the electric force is parallel to the electric field, the electric and magnetic fields must be _________ to each other. What is this region have? F(B) = F(E) v=?

perpendicular, crossed fields E/B

Since a charged particle moving ______________ to a magnetic field experiences a force due to the field, a current carrying conductor perpendicular to a magnetic field will experience a force since a current is ________ _______. The magnitude of the force depends on what thee things? F = ?

perpendicular, moving charge strength of the field, the current, and the length of the conductor in the field (F=BIL).

A charged particle moving perpendicular to a magnetic field can be made to travel in a straight line path by applying an electric field of _______________________.

proper strength and direction

Other equations related to crossed fields. qvB = ? E = ?

qE vB

Equating the centripetal force with the magnetic force what equation do you get?

qvB=mv²/r

Like poles _______, unlike _________

repel, attract

define Ferromagnetic materials

substances such as iron, cobalt, and nickel that exhibit magnetic properties when exposed to an external magnetic field.

Magnetism in a substance is a result of what?

the alignment of the magnetic domains

how are the domains arranged in unmagnetized ferromagnetic substances? how are the domains arranged in ferromagnetic substances exhibiting magnetic properties?

the domains are randomly arranged the domains are predominantly aligned in one direction

What is Magnitude of magnetic field is determined by?

the force the field exerts on a moving charge

The strength of the magnetic field depends upon what three factors?

the magnitude of the current, the number of coils per unit length, and whether or not an iron (ferromagnetic) core is inserted.

The direction of the magnetic field produced by a moving charge can be found by using what rule? Describe the rule?

the right hand thumb rule. Point your thumb in the direction of the current (flow of positive charge) and your fingers coil in the direction of the field.

Any particle that has this speed (according to v = E/B ), regardless of its mass or charge, will traverse the space ____________. This arrangement of fields is often used as a ______________, which is a device that allows only particles with specific speeds to pass.

undeflected, velocity selector

Since the magnetic force is a centripetal force, the magnetic force can do no ________ on a charged particle. That is, the magnetic force cannot change the ________ or the ___________ of a particle.

work, speed, kinetic energy

In order for a charge to experience a magnetic force, what two conditions must be met?

1. The charge must be moving, for no magnetic force acts on a stationary charge. 2. The velocity of the moving charge must have a component that is perpendicular to the direction of the magnetic field; parallel motion experiences no force.

The magnitude of the force depends on what three main things?

1. the strength of the field 2. the magnitude of the charge 3. the component of the velocity that is perpendicular to the field

What is the equation for the force felt by a magnetic field?

F(B)=qvB sin(x)

By varying current and distance from the wire, one finds that B is proportional to the current and inversely proportional to the distance from the wire. What is B (magnetic field) for this situation?

B=(µ₀/2π) (I/r)

What is the equation for B, the magnitude of the magnetic field felt as a force on a moving charge?

B=F/qv sin (x)

What is the equation for a solenoid magnetic field (B) with a bar and without a bar?

B=µ₀nI B=kµ₀nl

Magnetic field set up by a current loop is similar to that of ____________

Bar Magnet

since moving charges produce ___________, a moving charge placed in an external magnetic field will experience a _______ due to the field.

Magnetic field, force

Direction of the magnetic field, B, at any location is the direction in which the _________ of a compass needle points at that location.

North Pole

The polarity of the loop of wire can be found using what? and how do you use it?

Right hand. Coil your fingers in the direction of the current and your thumb will point north.

What is a solenoid or electromagnet?

a device consisting of a wire bent into a coil of several closely spaced loops that is magnetic when a current passes through the coil.

What does a galvanometer measure? How is it set up?

a galvanometer measures the magnitude of the current in the wire. In its simplest form, a galvanometer consists of a wire coil situated in a magnetic field. When current passes through the coil, torque due to the magnetic force on a current carrying wire causes the coil to twist. The angle to which the coil rotates depends upon the magnitude of the current.

what happens if the domains are permanently and uniformly aligned?

a permanent magnet is produced

Magnetic force between two parallel conductors Since a current carrying wire produces a magnetic field, two parallel wires each carrying a steady current exert forces on each other. Application of the right hand rules will show that the forces are __________ if the currents are in the same direction and __________if the currents are in opposite directions.

attractive, repulsive