practice homework questions Flashcards
You use a current-carrying straight conductor to produce a magnetic field. Which three properties of the magnetic field can you control?
- starting or stopping electric current strength of magnetic field
- increase or decrease direction of magnetic field
- changing direction of electric current
If two parallel wires are placed beside each other and current is sent down each wire in the same direction, will the wires repel or attract one another?
If the current is sent down both wires in the same direction, the magnetic field lines will go in opposite directions in between the 2 wires
-they will attract one another
What would the addition of a soft-iron core do to the strength of an electromagnet?
adding a soft iron core would increase the strength of an electromagnet
A glass cooking pot with an iron handle is placed on the cooking surface of an induction cooker. Describe the temperature of the glass and the handle after being on the induction cooker for some time.
An induction cooker can’t induce an electric current in the glass, so the pot would remain at room temp.
The cooker can induce an electric current in the iron handle so it would be at a very high temp
Before going through a metal detector at an airport, you may have to remove your belt, empty your pockets, and remove your shoes. Explain why.
these items contain metal that will be detected by the metal detector
benefits of induction chargers
induction charging is highly useful for electric devices that are exposed to water (safer than charging with wires)
disadvantages of induction chargers
less efficient than direct wired contact and has an increased resistive heating relative to direct contact
Electromagnetism is magnetism produced by an _______ current. When electric current flows through a wire, it creates a _______ field that surrounds the wire in circles. If more current flows through the wires, the magnetic field is _______.
electric; magnetic; stronger
electromagnet
An electromagnet is a solenoid wrapped around a bar of iron or other ferromagnetic material
solenoid
A solenoid is a coil of wire with electric current flowing through it.
Two major advantages of electromagnets
they are extremely strong magnetic fields
the magnetic field can be turned on and off
unit of electrical energy
joules
where are magnetic field lines strongest
at the poles
two parallel wires with opposing currents have what effect on each other
repel each other
true or false
in a circuit, electrons flow in the opposite direction to the conventional current
true
