3.9 magnetic fields

Question 1

define a magnetic field

Answer 1

a region of space in which moving objects with charge experience a magnetic force.

Question 2

rules for magnetic field lines

Answer 2

Never cross.
Lines that are closer together show a stronger field.
Always closed loops.

Question 3

what symbols show current going in and current going out of a wire

Answer 3

x = IN TO
● = OUT OF

Question 4

what is Magnetic flux density

Answer 4

Its direction is that in which the North pole of a freely-pivoted magnet points.
Its magnitude is defined by
B = F / IL
in which F is the force on a length l of wire, carrying a current I, placed perpendicular to the direction of the field.

Question 5

is magentic flux density vector or scalar

Answer 5

vector

Question 6

Linacs or linear accelerators

Answer 6

accelerate particles in a straight line and do not use Magnetic fields.

Question 7

Cyclotrons

Answer 7

do use magnetic fields so that they can accelerate particles in a circular path with an increasing radius.

Question 8

Synchrotrons

Answer 8

do use magnetic fields to accelerate particles around a circular path.

They increase the strength of the magnetic field and frequency of the pd.

Question 9

physical process by which Hall voltage is created

Answer 9

when a conductor carrying a current is placed in a magnetic field, the charge carriers (usually free electrons) moving through the material experiences a magnetic force at right angles to both the direction of the current and magnetic field. this force deflects the carriers to one side of the conductor, creating a separation of charges

Question 10

ways to make the magnetic field of a solenoid stronger

Answer 10

Increase the number of turns
Increase the current
Add a soft iron core

Question 11

what must you remember for electrons

Answer 11

reverse direction - as charge is negative

Question 12

Why do the tubes get progressively longer in a linac?

Answer 12

The particles gain speed (and therefore kinetic energy) as they pass through the gaps between the tubes. Because the alternating voltage changes polarity at a constant frequency, the time spent within each tube must be constant. As the speed increases, the length of the tubes must increase to ensure the particle spends that same amount of time in each tube