Electric Fields

Question 1

A moving charge….

Answer 1

Produces a magnetic field

Question 2

Magnitude of force applied between two charged particles is given by…

Answer 2

The magnitude of the charge and the distance between the charged objects

Question 3

An electric field is

Answer 3

The region of space around a charge

Question 4

Electric field strength

Answer 4

Determined by how close together the field lines are

The closer the lines, the greater the force

Question 5

Electrical Potential

Answer 5

The amount of energy from a supply required to move a charge of one coulomb to a point within the electric field

Question 6

Potential Difference

Answer 6

The difference in potential between the two points

Question 7

A stationary charge has

When it moves it has

Answer 7

An electric field around it

A magnetic field is created

Question 8

Right hand grip rule

Answer 8

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

Question 9

Left hand rule

Answer 9

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

Question 10

A particle Accelerator is

Answer 10

A device that uses electric and magnetic fields to accelerate charged particles to very high speeds

Question 11

Linear Accelerators/Linacs (3 Points)

Answer 11

• 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

Question 12

Disadvantage of a linear accelerator

Answer 12

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

Question 13

Circular Accelerators/Cyclotron (4 Points)

Answer 13

• 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

Question 14

Benefits of cyclotrons

Answer 14

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

Question 15

Disadvantage of cyclotrons

Answer 15

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

Question 16

Synchrotrons (3 Points)

Answer 16

• 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

Question 17

Benefits of synchrotrons

Answer 17

• 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

Question 18

Many synchrotrons produce

Answer 18

High energy X Ray’s for spectroscopy where atom structure can be investigated

Question 19

A charged particle in an electric field

Answer 19

Experiences a force which can make the particle accelerate

Question 20

One volt is

Answer 20

One joule per Coulomb

Question 21

Fields exist…

Answer 21

Around charged particles and between parallel plates

Question 22

Charged Particles in Linear Accelerators are accelerated by

Answer 22

A series of alternating electric fields

Question 23

Linear accelerators and Cyclotrons are used in

Answer 23

Fixed-Target experiments

Question 24

Synchrotrons are used in

Answer 24

Colliding beam experiments

Question 25

Charged particles in a cyclotron are accelerated by

Answer 25

Alternating electric fields

Question 26

Particles in a cyclotron travel….

As a result of….

Answer 26

In a spiral of increasing radius as a result of a constant magnetic field which is perpendicular to the spiral

Question 27

The diameter of a cyclotron is limited by

Answer 27

The physical size of the magnet

Question 28

In a synchrotron charged particles travel…

And are accelerated by…

Answer 28

In a circular path of fixed radius as a result of c shaped magnets of varying strength
Alternating magnetic fields