Electromagnetism Flashcards
What is ‘Electric Field Strength’
The force per unit positive charge.
What is ‘electrostatic potential’
The work done to bring a unit positive charge from infinity to a point in an electric field.
What is a magnetic field
A place where a moving charge experiences a force
Why will a current carrying wire experience a a force in a magnetic field
it creates its own magnetic field
Why do charged particles sometimes travel in a helical path?
The constant velocity parallel to the magnetic field combines with the circular motion perpendicular with the magnetic field
What is the equation for period of a helix?
T= 2pi x mass / qxB
What is the equation for the pitch of a helix?
P= ( v x 2pi x mass / q x B ) cosx
How many time constants equal the time to fully charge a capacitor
5
What is capacitive reactance
The opposition of a capacitor to changing current
What is back EMF
The opposition to changing current. This can be thought if as a large voltage used to oppose the change in current
What is it meant by self-inductance
When a current flows through a coil of wire a magnetic field is induced around it. The magnetic field which is created always opposes the change in current which created it in the first place
Why does the current not reach its max value immediately when a switch is closed in a circuit with an inductor in it.
Closing the switch tries to increase the current. This change in current causes a change in magnetic field. This changing magnetic field causes the inductor to create a large back EMF. This large back EMF causes a delay in the current reaching its max value
What is inductive reactance
The opposition of an inductor to changing current
If frequency increases in a circuit what will happen to the current, reactance and voltage in a capacitor and inductor
In a capacitor the current will increase which causes a small reactance and voltage
In a inductor the current will decrease which causes a big reactance and voltage
small frequency would be the opposite
What does the the speed of light equation show
that all electromagnetic waves regardless of frequency or wavelength travel at the speed of light
