Ch. 8 Electromagnetism and Magnetic Induction: Key Concepts and Rules

Q: The branch of physics that deals with the relationship between electricity and magnetism is called?

Electromagnetism

Q: A magnetic field surrounds a conductor carrying an electric current. True or False?

True

Q: According to the left hand rule, if a wire is held in the left hand with the thumb pointing in the direction of the current, what do the fingers indicate?

The direction of the magnetic field

Q: A wire coil is called a?

Helix

Q: When a current flows in a wire coil, one end behaves as the ____ pole and the other as the ____ pole.

North, South

Q: To determine which end of the coil is north and south pole, wrap the fingers of the left hand around the wire in the direction of the current. What does the thumb point to?

The North pole

Q: A helix carrying an electric current is called a?

Solenoid

Q: A solenoid with an iron core is called an?

Electromagnet

Q: Magnetic fields can induce electric currents in a process known as?

Electromagnetic Induction

Q: When a conductor cuts across a magnetic field, what is induced?

An EMF (electromotive force)

Q: Interaction between a magnetic line of force and a conductor is called?

Flux linkage

Q: As the number of flux linkages per second increases, what happens to the induced emf?

It increases

Q: As the strength of the magnetic field increases, what happens to the induced emf?

It increases

Q: As the angle between the conductor and the magnetic field approaches 90 degrees, what happens to the induced emf?

It increases

Q: As the number of turns in a coil increases, the magnitude of the induced emf?

Increases

Q: According to the left hand rule, if the thumb and first two fingers of the left hand are held at right angles, what do they represent?

Thumb = Motion, Index = Field, Middle = Current

Q: Where are solenoids found in the x-ray machine?

Locks of x-ray machine

Q: Where are electromagnets found in the x-ray machine?

Remote control switches and relays

Q: List three ways to induce voltage in a wire by electromagnetic induction.

magnetic flux is stationary - wire is moving, Wire is stationary - magnetic flux is moving, Magnetic flux is changing in strength - wire is stationary

If an open switch in a direct current circuit containing a coil is closed, an emf will be induced in the coil is the opposite direction of the applied emf. This is an example of ___

Self induction

During self induction, when the switch is first closed a ____ build up around the coil causing induced emf that opposes the direction of the applied emf

magnetic field

when the switch is closed the magnetic field is constant and does not move relative to the coil. The self induced emf ___

increases

if the switch is then opened the magnetic field collapses across the coil in the reverse direction. The self induced EMF ___

falls to zero

closing the switch is referred to as

make

opening the switch is referred to as

to break

placing a pair of insulated wire coils side by side and applying an alternating current to one will induce an EMF in the other in a process called ______

mutual induction