Watch Hewitt-Drew-it! Electromagnetic Induction #102 and complete #1 through #18
below.
1. In 1831 two physicists, _______________ in England and ______________ in
America made a discovery that changed the world. Both found that when a magnet is
moved into a coil of wire an _______________ was established in the wire. No battery
was needed.
2. In the following demonstration, an induced electric current occurs when the magnet is
_________ inside the coil. This method of producing electric current is called
_________________. The quicker the magnet is moved, the __________ the induced
voltage.
3. A current is produced in a wire by a voltage. As shown below, a __________ can be
induced by the __________ of a magnet relative to a wire or
the motion of the __________ relative to the _____________. To induce a voltage by
electromagnetic induction, only _____________ motion between magnet and wire is
needed. The greater the relative motion between __________ and __________, the
greater the _________________.
4. The amount of induced voltage also depends on the number of _________ of
___________ involved. More coils, ________ voltage.
5. What was Faraday’s response to his queen’s question of what importance was his
electromagnetic induction?
6. Faraday’s discovery became the underbelly of the _________________.
7. His discovery allowed for the production of ample _________. Motors could be built,
factories could house them, and workers could produce goods as never before. Keep in
mind, however, that electromagnetic induction is not an _________________!
______________ is done to produce relative motion between ____________ and
______________.
8. The amount of electrical energy _____________ is the same as the ___________
done in producing it. Electricity is a ____________ of energy, not a ____________.
Note where the mechanical input and the electrical output are located in the figure
below. Also note the rotating loop and magnet.
9. Another way to produce current in a coil of wire is with another coil in which
_________ undergoes a change. The coil in which the current is changed is called the
__________ coil. When the current is changed, ____________ is induced in the
secondary circuit, known as the ______________ coil.This is because the magnetic
field of the primary undergoes a ___________. Note the primary and secondary coils in
the figure below.
10. To increase the electromagnetic induction in the secondary coil, an iron core is
inserted through both. This arrangement is called an ______________________.
Fill in the blanks below with the words primary, secondary, and ac input and then sketch
the magnetic field lines set up by the primary coil.
11. Changes of voltage and therefore current and its magnetic field in the primary
induces voltage in the secondary. In this way electric power can be transferred from one
coil to the other and the voltages involved depend on the relative number of turns on
each coil.
12. If the secondary coil had more turns than the primary coil, the voltage induced in the
secondary would be __________ than the voltage in the primary. This does not mean,
however, that there is a multiplication of __________ or ____________. As the voltage
goes up in one coil, the current ___________ in the other.
V
I
13. Power equaling IV can mean I , voltage _________ up or v , voltage stepped
_________. Like in all areas of physics, the conservation of ___________ reigns.
14. Show the induced voltages in the secondary coils as measured by the meters.
15. In about 1860, _________________ stated that an electric field is induced in any
region of space in which a magnetic field is ____________ with __________ and a
magnetic field is induced in any region of space in which an _______________ is
changing with _______________.
16. Electromagnetic waves pass right through one another. The space around you is
filled with ___________, ____________, ________________, and ___________ each
doing its own thing while ignoring all the others all in accord with Maxwell’s statements.
17. Maxwell was the first person to know what starlight was. He knew that light of any
kind is ___________carried in waves of __________ and_________ fields that
continually ___________ each other.
18. Because of electromagnetic induction, the energy of elevated rivers has been
harnessed, turned to electricity, and transported to distant cities. The advent of motors,
generators, and transformers occurred about the same time that the American Civil War
was being fought.