Unit 2 - Electric Fields and Magnetic Fields Flashcards
Definition of Electric Field
The region that surrounds electrically charged particles in which a force (the electrostatic force) is exerted on other electrically charged particles.
Definition of electric field strength
The electrical force acting on unit positive charge
Definition of electrical potential
The work done in moving unit positive charge from infinity to that point
The energy required to move charge between two points in an electric field is…
Independent of the path taken
State the use of the equation and define the symbols in:
E = F/Q
Used to find the electric field strength in both a radial and uniform electric field
F - Force on the charged particle (N)
Q - Charge (C)
E - Electric field strength (N C-1)
State the use of and define the symbols in:
V = Ed
Used to find the potential difference in a uniform field
V - Potential Difference (V)
E - Electric field strength (V m-1)
d - distance (m)
State the use of and define the symbols in
W = QV
Used to find the work done in moving a charged particle from infinity to a point
W- Work done (J)
Q - Charge (C)
V - Potential Difference (V)
Definition of an electronvolt (eV)
Energy acquired when one electron accelerates through a potential difference of one volt.
Fill in the missing words:
Electrons are in ______ around ________and individually produce a ___________.
Electrons are in motion around atomic nuclei and individually produce a magnetic effect.
Explain ferromagnetism
Some metals for example, iron, nickel, cobalt, and some rare earth (metals) exhibit a magnetic effect called ferromagnetism, in which magnetic dipoles can be made to align, resulting in the material becoming magnetised.
Definition of magnetic field
The space around an object where a moving charge will experience a force
Definition of Magnetic induction
The strength of a magnetic field at a point.
Denoted by B
Units are the Tesla (T)
Direction of B is the direction of the magnetic force at that point.
State the use of and define the symbols in:
F = BILsin(pheta)
Used to calculate the force being exerted on a conductor / current carrying wire in a magnetic field.
F - Force on current carrying wire (N)
B - Magnetic Induction (T)
L - Length of the wire (m)
pheta - Angle between the wire and direction of the magnetic field
Why is the force on a current carrying wire greatest when the current is perpendicular to the magnetic field
When the current is perpendicular, pheta = 90 degrees, therefore sin(pheta) = 1.
1 is the maximum value sin(pheta) could have and since F = BILsin(pheta), F would be greatest when sin(pheta) = 1.
Therefore F would be greatest when the current is perpendicular to the magnetic field.
Define a Magnetic induction of 1 Tesla in terms of Newtons, Amps and metres when pheta = 90 degrees
1 N A-1 m-1
1 Newton Per Amp-Metre / 1 Newton per Amp per Metre
