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Electromagnetism and DC Motor

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Questions and Answers

What is the unit of magnetic flux?

Wb/m

Weber (correct)

Tesla

Henry

What is the purpose of the commutator in a DC motor?

To produce a rotating magnetic field

To supply electrical current to the armature winding (correct)

To convert mechanical energy into electrical energy

To convert electrical energy into mechanical energy

What is the term for the direction of force in a DC motor?

Lenz's law

Fleming's right hand rule

Fleming's left hand rule (correct)

Faraday's law

What is the function of the stator in a DC motor?

To produce a stationary magnetic field Signup and view all the answers

What is the term for the magnetic field strength?

Magnetic field strength Signup and view all the answers

What is the effect of increasing the number of turns around a core and/or increasing the current through the coil on the magnetic field strength?

The magnetic field strength increases. Signup and view all the answers

What is the unit of measurement for the magnetomotive force (mmf)?

Ampere-turns (At) Signup and view all the answers

What is the permeability of nonmagnetic materials, such as copper, aluminum, wood, glass, and air, compared to that of free space?

Same as that of free space Signup and view all the answers

What is the relationship between the magnetic field strength and the type of core used in an electromagnet?

The magnetic field strength is affected by the permeability of the core material. Signup and view all the answers

What is the analogy between magnetic circuits and electric circuits?

Magnetomotive force is analogous to applied voltage. Signup and view all the answers

What is the purpose of placing certain materials, such as iron, steel, or cobalt, within a coil?

To increase the magnetic field strength. Signup and view all the answers

What is the primary factor that determines the strength of a magnetic field in a particular region?

The density of flux lines in that region Signup and view all the answers

What happens when unlike poles of two permanent magnets are brought together?

The magnets attract and the flux distribution is strengthened Signup and view all the answers

How can the direction of the magnetic flux lines be determined?

By placing the thumb of the right hand in the direction of conventional current flow and noting the direction of the fingers Signup and view all the answers

What is the characteristic of a magnetic field around a permanent magnet?

It is represented by magnetic flux lines Signup and view all the answers

What is the relationship between the magnetic field strength and the density of flux lines in a particular region?

The magnetic field strength is directly proportional to the density of flux lines Signup and view all the answers

What is the result of bringing like poles of two permanent magnets together?

The magnets repel and the flux distribution is disrupted Signup and view all the answers