Physics 1142 Self Test

In some devices, induction heating is used to ...

heat metal parts without heating other nonconducting parts

The basic building blocks of electronic circuits are ..., ..., ..., ..., and ...

resistors, capacitors, diodes, triodes, transistors

Name the three basic parts of a transformer

soft iron core, primary coil, secondary coil

Describe the process of electron movement within a semiconductor

An electron makes its way toward the positive side of the crystal, which attracts it, by going from hole to hole

What are eddy currents?

Eddy currents are electrical "swirls" induced in circuits by changing magnetic fields

Describe the function of the armature in an electric generator

The armature rotates between the poles of a field magnet, inducing electric current

What is the equivalent mass of an element?

The equivalent mass of an element is its atomic mass divided by its valence

What is the main advantage of connecting cells in parallel rather than in series?

When cells are connected in parallel, they can deliver larger current intensities than when those same cells are connected in series

Name three basic parts of a voltaic cell

a cathode, an anode, an electrolyte

Electrolysis is the separation of ...

a molecule into its respective elements by passing an electric current through an electrolyte

... bonds form when atoms share electrons; ... bonds form when ions are held together by their opposite charges

covalent, ionic

Define self-induction

Self-induction is the destructive interaction between a current and the magnetic field it produces

What are the advantages of semiconductor devices over regular triode and diode tubes?

Semiconductor devices are small, use little power, generate only a slight amount of heat, require no warm-up time, and can withstand shock. They do not require a hot filament or a vacuum enclosure.

Why would the combination of sodium and magnesium not make a useful voltaic cell?

Sodium and magnesium would not make a useful voltaic cell because their electrochemical potentials differ only slightly

Michael Faraday

first discovered two laws of electrolysis

State Lenz's law

A current induced by electromagnetic forces always acts to oppose those forces

What is atomic mass?

Atomic mass is the mass of an atoms compared to the mass of a carbon - 12 atom, which is set equal to 12.00

State Faraday's first lay of electrolysis

The mass of an element released at an electrode during electrolysis by a steady current is directly proportional to the quantity of electric current passing through the electrolyte

What is valence?

Valence is a measure of the combining power of atoms

Heinrich Lenz

discovered induced currents that oppose electromagnetic forces

Humphry Davy

discovered that electrolysis could free metals from their ores

Joseph Henry

discovered the electromagnetic induction at the same time as Michael Faraday

Alessandro Volta

discovered the voltaic cell; made the first battery

Lee De Forest

established a radio station

John Fleming

invented the diode

William Shockley

invented the transistor

George Westinghouse

preferred alternating current for commercial use

Thomas Edison

preferred direct current for his experiments

if the voltage is doubled, ...

the current decreases by 50%

If the voltage is reduced by half, ...

the current doubles

Name the three parts of the transistor and describe their functions

the emitter- supplies the electrons and acts as the filament the base- center layer of the transistor and acts as the grid the collector- accepts the electrons and acts as the plate

State Faraday's second law of electrolysis

the mass of a substance liberated at the electrodes during electrolysis by a steady current is proportional to the equivalent mass of that substance

If the current is to be doubled, ...

the voltage is decreased by 50%

If the current is to be reduced by half, ...

the voltage is doubled

The release of electrons from a heated metal surface is called ... emission

thermionic