Electric Fields Flashcards
A moving charge….
Produces a magnetic field
Magnitude of force applied between two charged particles is given by…
The magnitude of the charge and the distance between the charged objects
An electric field is
The region of space around a charge
Electric field strength
Determined by how close together the field lines are
The closer the lines, the greater the force
Electrical Potential
The amount of energy from a supply required to move a charge of one coulomb to a point within the electric field
Potential Difference
The difference in potential between the two points
A stationary charge has
When it moves it has
An electric field around it
A magnetic field is created
Right hand grip rule
To determine the direction of the magnetic field lines when drawing diagrams
Thumb represents the direction of the current
Your fingers curl in the direction of the magnetic field lines
Left hand rule
To determine the direction of the force on a current-carrying wire
Middle finger gives the direction of the current
First finger gives the field direction
Thumb gives the direction of force or motion on the current carrying wire
A particle Accelerator is
A device that uses electric and magnetic fields to accelerate charged particles to very high speeds
Linear Accelerators/Linacs (3 Points)
- A charged particle is attracted towards a plate in a ‘drift’ tube
- Particle passes through one of these tubes and is accelerated towards the next, passes through and is accelerated to the next and so on
- The field between each drift tube must change rapidly so that each (new) tube attracts the particle leaving the previous tube
Disadvantage of a linear accelerator
Particles are kept in the centre by magnets In order to increase the energy and velocity of these particles means the accelerator must be long and makes the cost of construction high
The final energy of the particles is limited by the length of the accelerator
Circular Accelerators/Cyclotron (4 Points)
- High frequency voltage supply accelerates the particles
- Consists of two D-Shaped sections (‘dees’) which have a small gap and a high potential difference between them
- Charged particle is accelerated across the gap then bent inside one of the Dee’s until it is in the opposite direction
- Particles accelerated across the gap until the particle is at the correct energy - where it is released for the experiment
Benefits of cyclotrons
Circular nature - magnets keep particles in a circular orbit - means that it can be smaller than a linear accelerator meaning that it would be cheaper to make
Disadvantage of cyclotrons
As the particle becomes faster its path radius increases and it moves further out towards the edge of the dees
At very high speeds, relativistic effects interfere with the efficient operation of the cyclotron and it can be difficult to adapt the fields in line with the particle
Synchrotrons (3 Points)
- A specific type of circular accelerator
- Magnetic and electromagnetic fields have been adapted to produce a very energetic and narrow ring of charged particles at high energies
- Usually built in order to produce radiation for experiments and medical applications rather than to accelerate particles for investigation
Benefits of synchrotrons
- When particles are accelerated rapidly and have to travel in curved paths synchrotron radiation is emitted
- Energy loss can occur during these particle physics experiments
- Synchrotrons can be built so that radiation is produced at certain frequencies for scientific and medical purposes
- They can produce highly energetic photons across a range of frequencies
Many synchrotrons produce
High energy X Ray’s for spectroscopy where atom structure can be investigated
A charged particle in an electric field
Experiences a force which can make the particle accelerate
One volt is
One joule per Coulomb
Fields exist…
Around charged particles and between parallel plates
Charged Particles in Linear Accelerators are accelerated by
A series of alternating electric fields
Linear accelerators and Cyclotrons are used in
Fixed-Target experiments
Synchrotrons are used in
Colliding beam experiments
Charged particles in a cyclotron are accelerated by
Alternating electric fields
Particles in a cyclotron travel….
As a result of….
In a spiral of increasing radius as a result of a constant magnetic field which is perpendicular to the spiral
The diameter of a cyclotron is limited by
The physical size of the magnet
In a synchrotron charged particles travel…
And are accelerated by…
In a circular path of fixed radius as a result of c shaped magnets of varying strength
Alternating magnetic fields
