magnetism and electricity Flashcards
(26 cards)
What is magnetism?
Magnetism is a physical phenomenon produced by the motion of electric charge, resulting in attractive and repulsive forces between objects.
True or False: A magnetic field is created by moving electric charges.
True
Fill in the blank: The area around a magnet where magnetic forces can be detected is called the __________.
magnetic field
What are the two types of magnetic poles?
North pole and South pole
What happens when like magnetic poles are brought together?
They repel each other.
What happens when opposite magnetic poles are brought together?
They attract each other.
Define ‘electromagnet’.
An electromagnet is a type of magnet in which the magnetic field is produced by an electric current.
What is the right-hand grip rule used for?
To determine the direction of the magnetic field around a current-carrying conductor.
True or False: The strength of an electromagnet can be increased by increasing the number of coils of wire.
True
What is electromagnetic induction?
Electromagnetic induction is the process of generating an electromotive force (EMF) in a conductor by a changing magnetic field.
Who discovered electromagnetic induction?
Michael Faraday
Fill in the blank: The unit of magnetic flux is the __________.
Weber
What does Faraday’s law of electromagnetic induction state?
The induced EMF in a closed loop is proportional to the rate of change of magnetic flux through the loop.
What is Lenz’s law?
Lenz’s law states that the direction of the induced current is such that it opposes the change in magnetic flux that produced it.
True or False: A transformer works on the principle of electromagnetic induction.
True
What are the two main components of a transformer?
Primary coil and secondary coil
What is the formula for calculating the voltage in a transformer?
Vp/Vs = Np/Ns, where V is voltage and N is the number of turns.
Fill in the blank: The phenomenon where a changing magnetic field induces an electric current is known as __________.
electromagnetic induction
What is the purpose of a generator?
To convert mechanical energy into electrical energy using electromagnetic induction.
Define ‘magnetic flux’.
Magnetic flux is the product of the magnetic field strength and the area perpendicular to the field through which the field lines pass.
What is the SI unit for electromotive force (EMF)?
Volt
True or False: Electromagnetic induction can occur with a stationary magnetic field.
False
What is the difference between AC and DC in terms of current?
AC (Alternating Current) changes direction periodically, while DC (Direct Current) flows in one direction only.
What role does a commutator play in a DC motor?
A commutator reverses the direction of current in the motor windings, ensuring continuous rotation.
