general electricity

Question 1

what are 5 sources of electrical energy

Answer 1

magnetism, chemical energy, light, heat, pressure

Question 2

which law of electricity is the most important for an aircraft mechanic to know

Answer 2

ohms law

Question 3

what are the elements of ohms law

Answer 3

voltage E, current I, resistance R (volts, amps, ohms)

Question 4

what is the name of the law that describes the relationship in an electrical circuit of voltage, current, resistance

Answer 4

ohms law

Question 5

what is the basic equation of ohms law

Answer 5

E=IxR

Question 6

what is meant by resistance in an electrical circuit

Answer 6

the opposition to flow of electrons

Question 7

what is the basic unit of electrical resistance

Answer 7

the ohm

Question 8

what four things affect the resistance of an electrical conductor

Answer 8

the material, the cross sectional area, the length, the tempature

Question 9

how can you tell the resistance of composition resistor

Answer 9

by a series of colored bands around one end of the resistor

Question 10

what formula is used to find resistance when voltage and current are known

Answer 10

resistance= voltage divided by current

R= E/I

Question 11

what is the formula for power in DC circuit

Answer 11

power= voltage times current (P=ExI)

Question 12

what is the relationship between mechanical and electrical power

Answer 12

1 horsepower= 746 watts

Question 13

what is meant by true power in an AC circuit

Answer 13

the product of the circuit voltage and the current that is in phase with this voltage

Question 14

in what units is true power expressed

Answer 14

in watts

Question 15

what is meant by apparent power in an AC circuit

Answer 15

the product of the circuit voltage and the circuit current, without reference to phase angle

Question 16

in what units is apparent power expressed

Answer 16

in volt-amps

Question 17

what is meant by reactive power in an AC circuit

Answer 17

the power consumed in the inductive and capacitive reactances in an AC circuit reactive power is also called wattless power

Question 18

in what units is reactive power expressed

Answer 18

in volt amps reactive, or kilovolt amps reactive

Question 19

what is meant by power factor in an AC circuit

Answer 19

the ratio of true power to apparent power. it is also the ratio of circuit resistance to circuit impedance

Question 20

how many watts of power are consumed by 1/5 horsepower, 24 volt DC motor that is 75% efficient

Answer 20

efficiency= power out/ power in
199 watts