Science Ch.19-21

How many paths through which charge can flow would be shown in a circuit diagram of a series circuit?

1

The current in a hair dryer measures 15.0 amps. The resistance of the hair dryer os 8 ohms. What is the voltage?

120 V

If a step-ip transformer has a primary coil with 15 turns, how many turns would be required in the secondary coil in order to increase the voltage from 80 volts to 160 volts?

30 turns

A transformer has a primary coil with 600 turns and a secondary coil with 300 turns. If the output voltage is 320 volts, what is the input voltage?

640 volts

The force a magnet exerts on another magnet, on iron or a similar metal, or on moving charges is....

A magnetic force

A ferromagnetic material that has domains that remain aligned for a long period of time is called

A permanent magnet

if a negative and positive charged objects were brought close to each other they would

Attract each other opposites attract!

A vacuum tube can be used to

Change alternating current into direct current, Increase the strength of a signal, AND turn a current on or off.

Which of the following provides electrical safety?

Circuit breaker, Fuse, AND Ground-fault circuit interrupter

A DC generator is similar to an AC generator except that in

DC generators, commutators produce direct current.

Which statement describes magnetic field lines at the north pole and south pole of a bar magnetic?

Field lines begin near the magnet's north pole extend toward its south pole

How can a permanent magnet be demagnetized?

Heat the magnet up AND Strike the magnet with a heavy blow.

Which of the following is the reason "soft" iron is used for the cores of electromagnets?

It is easily magnetized.

Which of the following statements describes the interaction between magnetic poles?

Like poles repel each other, and opposites poles attract each other.

Who is the BEST??

Lizzie Bowman!!

Moving a magnet inside a coil of wire will induce a voltage in the coil. How can the voltage in the coil be increased?

Move the magnet inside the coil of wire more rapidly.

Which of the following statements is true about current-carrying wire in a magnetic field?

Reversing the current direction will cause the force deflecting the wore to be perpendicular to the magnetic field but in the opposite direction.

WHich of the following is made from a crystalline solid that conducts a current only under certain circumstances?

Semiconductor

How does the magnetic force exerted by a magnet change as the distance between 2 magnets increases?

The magnetic force decreases.

Which of the following statements is true about Earth's magnetic poles?

They are the areas where Earth's magnetic field is weakest

How are step-up transformers used in the transmission of electrical energy?

They increase the voltage for efficient long-distance transmission

Which of the following rep. Ohm's law

V= I x R

The device that measures current in a wire by using the deflections of an electromagnet in an external magnetic field is..

a galvanometer.

A region that has a large number of atoms whose magnetic fields are lined up parallel to a magnet's field is

a magnetic domain

A coil of wire that is carrying a current and produces a magnetic field is..

a solenoid.

The type of current in your SCHOOL is mostly

alternating current

The strength of an electric field depends on the

amount of charge that produced the field AND distance from the charge

What do transistors do in a mobile phone?

amplify the phone's incoming signal

Which of the following materials allows charges to flowwwww easily?

an electrical conductor

Electronic signals that are smoothly varying signals produced by continuously changing the voltage or current in a circuit are

analog signals

If you break a bar magnet is half each half..

becomes a bar magnet with 2 poles

If the current in a wire is directed upward, what is the direction of the magnetic field produced by the current?

counterclockwise in the horizontal plane

What solid-state component in a mobile phone maintains proper voltage levels in the circuits?

diodes

What type of current is produced by a battery?

direct current

If you know the power rating of an appliance and the voltage of the line it is attached to, you can calculate the current the appliance uses by

dividing the power by the voltage

The process of generating an electric current by moving an electrical conductor relative to a magnetic fields is called

electromagnetic induction

Info sent as patterns and codes in the controlled flow of electrons through a circuit is a

electronic signal

An electrical insulator has

electrons tightly bonded to its atoms

Walking across a carpet is an example of charge being transferred by

friction

A device that changes mechanical energy to electrical energy by rotating a coil of wire through a magnetic field is called a(n)

generator

How are fossil fuels used to generate electrical energy?

heat from burning fuel creates steam that turns a transformer

Which of the following would reduce the resistance of a metal wire?

increasing its thickness

If a neutral metal comb is held near an object with a negative charge, the comb will become charged by

induction

A thin slice of silicon that contains many solid0state components is a(n)

integrated circuit

What is the name of the area surrounding Earth that is influenced by Earth's magnetic field?

magnetosphere

The electromagnet in a galvanometer..

moves a pointer along a numbered scale in response to a current

What creates a magnetic field?

moving electric charges

If an atom gains electrons, it becomes a

negatively charged ion

In figure 21-1, starting from the left what magnetic poles are shown on the 2 bar magnets?

north, south, north, south

The output voltage and current of a transformer are determined by the..

number of turns in the primary and secondary coils.

Most of the circuits in your home are

parallel circuits

If a current-carrying wire is in a magnetic field, in what direction will a force be exerted on the wire?

perpendicular to both the magnetic field and the current direction.

What is the dif. in electrical potential energy between 2 places in an electric field

potential dif.

A Ground-fault circuit interrupter shuts down a circuit if it

senses unequal currents.

Before electric current in power lines can be safe for your home, it must pass through a ....

step-down transformer

In an electric motor, periodically changing the direction of current in the electromagnet can cause the axle to spin b/c...

the magnetic field reserves direction.

Resistance is affected by a materials

thickness, temp., and length

A solid-state component with 3 layers of semi-conductors is a(n)

transistor

What is the unit of electrical power?

watt