Download electricity : answer key

ELECTRICITY : ANSWER KEY
SECTION REVIEW 4-1
1. ELECTRONICS STUDIES THE RELEASE, BEHAVIOR, AND EFFECTS OF
ELECTRONS USED TO CARRY INFORMATION. ELECTRICITY USES
ELECTRIC CURRENTS TO POWER DEVICES BY CONVERTING THE ENERGY
OF MOVING ELECTRONS INTO HEAT AND LIGHT ENERGY.
2. ELECTRONS IN A VACUUM TUBE FORM A CURRENT; A VACUUM TUBE IS
USED AS A RECTIFIER TO CHANGE ALTERNATING CURRENT (AC) INTO
DIRECT CURRENT (DC); VACUUM TUBES ARE USED IN AMPLIFIERS TO
INCREASE THE STRENGTH OF AN ELECTRIC SIGNAL.
3. SEMICONDUCTORS ARE DEVICES THAT CAN CONDUCT ELECTRICITY
BETTER THAN INSULATORS CAN, BUT NOT AS WELL AS METALS CAN.
4. AN INTEGRATED CIRCUIT COMBINES MANY DIODES AND TRANSISTORS
ON A THIN SLICE OF SILICON CRYSTAL, AND A SINGLE ITEGRATED
CIRCUIT MAY OFTEN CONTAIN THOUSANDS OF DIODES AND TRANSISTORS
IN A VARIETY OF COMPLEX COMBINATIONS. AN ADVANTAGE OF
INTEGRATED CIRCUITS IS THAT THEY ARE MUCH SMALLER AND HAVE
GREATER PERFORMACE THAN VACUUM TUBES.
SECTION REVIEW 4-2
1. IN DEVICES THAT TRANSMIT SOUND, SOUND VIBRATIONS ARE
CHANGED INTO ELECTROMAGNETIC WAVES, WHICH ARE THEN
CONVERTED BACK INTO SOUND VIBRATIONS.
2. TRANSMITTER AND RECEIVER. THE TRANSMITTER DETECTS
VIBRATIONS, CHANGING THEM INTO ELECTRIC CURRENT; THE RECEIVER
CHANGES THE ELECTRIC CURRENT BACK INTO SOUND VIBRATIONS.
3. ANSWERS MAY VARY SLIGHTLY. STUDENTS MIGHT SUGGEST THESE
STEPS: SOUND WAVES, MICROPHONE, AUDIO SIGNAL, TRANSMITTER,
TRANSMITTING ANTENNA, RADIO WAVES, AUDIO RECEIVING ANTENNA,
RECEIVER, AMPLIFIER, AND SOUND.
4. ACCEPT LOGICAL RESPONSES. STUDENTS MIGHT SUGGEST THAT
TELEPHONES AND RADIOS HAVE BECOME SMALLER IN SIZE AND MORE
PORTABLE.
SECTION REVIEW 4-3
1. IT IS AN ELECTRONIC DEVICE THAT USES ELECTRONS TO PROCUCE
IMAGES ON A SCREEN. AN ELECTRIC CURRENT HEATS A METAL
FILAMENT IN THE CRT, WHICH THEN EMITS ELECTRONS. THE ELECTRONS
ARE ACCELERATED THROUGH A MAGNETIC FIELD, WHICH FOCUSES THE
ELECTRONS INTO A BEAM. ELECTROMAGNETS PLACED OUTSIDE THE CRT
CAUSE THE BEAM OF ELECTRONS TO CHANGE DIRECTION. AT EACH
POINT WHERE THE ELECTRONS STRIKE THE FLUORESCENT MATERIAL OF
THE CRT SCREEN, VISIBLE LIGHT IS GIVEN OFF.
2. IN A COLOR CRT, THE SCREEN IS COATED WITH 3 DIFFERENT
MATERIALS THAT CAN GLOW WITH RED, BLUE, OR GREEN LIGHT. A
SIMPLE CRT HAS A COATING OF ONE MATERIAL. A COLOR CRT ALSO
DIFFERS FROM A SIMPLE CRT IN THAT IT HAS 3 ELECTRON “GUNS”
RATHER THAN JUST ONE.
SECTION REVIEW 4-4
1. AN ELECTRONIC DEVICE THAT PERFORMS CALCULATIONS AND
PROCESSES INFORMATION. THE HARDWARE OF A COMPUTER EXECUTES
INSTRUCTIONS AND COMMANDS, AND THE SOFTWARE PROVIDES THE
INSTRUCTIONS, OR THE STEPS, FOR THE COMPUTER TO FOLLOW.
2. A MODEM IS BOTH AN INPUT AND AN OUTPUT DEVICE. IT CAN INPUT OR
OUTPUT INFORMATION USING PHONE LINES AND CAN CONNECT WITH
HUGE BANKS ON INFORMATION (DATA BANKS) FOR USE BY THE
COMPUTER OPERATOR.
3. THE BINARY SYSTEM IS A MATHEMATICAL SYSTEM USING ONLY 2
NIMBERS, 0 AND 1. BECAUSE THE SWITCHES IN A COMPUTER CAN BE IN
ONE OF 2 POSITIONS, EITHER ON OR OFF, THE BINARY NUMBERS REFERS
TO A SWITCHING POSITION.