Electrical principles Flashcards
(23 cards)
What is magnetism?
A magnetic field associated with a bar magnet, represented by lines of force or magnetic flux flowing from north to south.
What is the unit of magnetic flux?
Webers (Wb)
What does flux density (B) measure?
The number of lines of flux passing through a given area, measured in webers/m² or teslas (T).
What is the formula for flux density?
B = φ / A
How is electricity produced in relation to magnetism?
Electricity is produced with the aid of a magnetic field and an electric current can produce a magnetic field.
What is the relationship between current and magnetic field strength (H)?
The greater the electric current, the greater the magnetic field strength, measured in amperes per metre (A/m).
What defines a conductor?
Substances with free electrons that allow electricity to flow easily.
What defines an insulator?
Substances from which electrons cannot easily break away.
What is the unit of voltage?
Volt (V)
What is current (I)?
The flow of electricity in a closed circuit, measured in amperes (A).
What is resistance (R)?
The opposition to current flow in a circuit, measured in ohms (Ω).
What is Fleming’s left-hand rule used for?
To determine the direction of force exerted on a current-carrying conductor in a magnetic field.
What does the right-hand grip rule illustrate?
The direction of the magnetic field around a current-carrying wire.
What did Michael Faraday demonstrate in 1821?
That a conductor moving in a magnetic field produces an electromotive force (emf).
What is the principle behind induction motors?
A moving flux crosses the rotor conductors, producing a force that causes the rotor to turn.
What do generators do?
Produce an emf by forcibly moving conductors through a magnetic field.
What are transformers used for?
To change the level of voltage, classified as step up or step down transformers.
Fill in the blank: The unit of inductance is _______.
Henry (H)
True or False: Electromagnetism only concerns the behavior of electric currents without any magnetic fields.
False
What is the symbol for magnetic flux?
φ (phi)
What happens when an atom loses an electron?
It becomes positively charged and can attract an electron from another atom.
What is the time constant of a circuit symbolized by?
Ꞇ (tau)
What is the relationship between the rate of change of magnetic flux and induced emf?
The magnitude of an emf induced is proportional to the rate of change of magnetic flux.
