Short Exam 6
T/F Uman says that tree protection serves to save trees from damage and to reduce risks to humans, animals and structures nearby
true
T/F When outside during a lightning storm you should never get under isolated trees to keep as dry as possible because water conducts electrical currents like those of lightning.
true
According to Uman, what is the apparent cause of the decrease in lightning deaths shown in Figure 7.2? a. The decrease in the number of people working outdoors b. Protective clothing for farmers and ranchers c. Tall buildings drawing the lightning d. The population increase
a
During the period 1959-1996, the percentage of lightning deaths that occurred in various and unknown situations was about 30% 18% 13% 28%
a
During the period 1960-1996, the percentage of lightning injuries that occurred on golf courses was about a. 3% b. 18% c. 13% d. 28%
a
How may lightning have played a role in the existence of the tall grass prairies of the Great Plains? a. by setting fires that make it favorable for grasses and discouraging for trees b. by providing nitrogen c. by inspiring native american art and culture of the great plains d. by striking and killing grazing animals like bison and antelope
a
The state with the highest per capita fatality rate over the period 1960 - 1990 isa. New Mexicob. Alaskac. South Dakotad. Hawaii
a
What are the damage characteristics of rough-barked evergreens struck by lightning? a. bark removed in long narrow strips b. bark torn off in large irregular patches or sheets c. leaves turn brown d. needles are shed
a
What fraction of trees that are struck by lightning are killed? a. a very small fractionb. a large fraction but less than halfc. a large fraction much greater than halfd. all
a
According to Uman, Storm Data may be underestimating the number of individuals injured by lightning in the US annually. Uman states that the more likley number is more thana. 300b. 500c. 450d. 345
b
During the period 1960-1996, the percentage of lightning injuries that occurred in situations involving farming, constructions, and heavy machinery was about a. 6%b. 4%c. 5%d. 3%
b
If a current of 200 Amperes flows through a telephone protection device into the ground through a ground rod with 30 Ohms of resistance, determine the voltage on the telephone wire.a. 5000 Voltsb. 6000 Voltsc. 3000 Voltsd. 6667 Volts
b
If, in Figure 7.9b, p.126, of the Uman text, the voltage across the body reached 1.0 megaVolts in about 1 microsecond during the return-stroke phase of a lightning strike to a human, what resistance does that number imply for the human body in this example?a. 100 Ohmsb. 700 Ohmsc. 350 Ohmsd. 900 Ohms
b
It would appear that lightning strikes with continuing currents are likely to cause forest fires. What is the duration of continuing current Uman says it takes to ignite woody fuels? a. a few microseconds b. about 100 milliseconds c. about 900 milliseconds d. about 0.2 seconds
b
Positive CG flashes are prime candidates for setting forest fires because a. positive charge is more energetic than negative charge b. they almost always have long continuing currents c. they are almost always single-stroke flashes d. they occur where the forests are
b
Protection of trees is done in much the same way as protection of structures, except thata. it has to be a lot less expensiveb. the lightning current has to be directed away from the major root systemc. you can use cheap aluminum wired. leaves get in the way
b
Roughly how many telephone-related lightning deaths occur annually in the US?a. 0b. 1 to 3c. 10d. 60
b
The fraction of lightning deaths and injuries that occur indoors isa. the majorityb. only a few percentc. about halfd. 90%
b
The state ranked lowest in injuries over the period 1959-1994 isa. Hawaiib. Alaskac. Pennsylvaniad. Florida
b
The state with the lowest per capita damage rate over the period 1960 - 1990 isa. New Mexicob. Californiac. South Dakotad. Hawaii
b
The state with the lowest per capita fatality rate over the period 1960 - 1990 isa. New Mexicob. Alaskac. South Dakotad. California
b
Uman lists ways in which humans can be killed or injured as a result of a lightning strike. Which of the ways listed below is not one of them? a. the current of a direct strike b. the N wave from thunder c. burns or smoke inhalation from lightning caused fires d. the current of an unconnected upward leader
b
What are the damage characteristics of smooth barked deciduous trees struck by lightning? a. bark removed in long narrow strips b. bark torn off in large irregular patches or sheets c. leaves turn brown d. needles are shed
b
What electrical principle determines the voltage in problems such as that in question 25?a. E = L di/dtb. V = IRc. B = 6.28 Id. E = kQ1Q2/r2
b
1. Which of the following is not listed as a factor in the risk of lightning injury?a. whether a structure incorporates lightning protectionb. what construction materials are usedc. the size of the windows in the structured. the size of the structure
c
According to Storm Data, the number of individuals injured by lightning in the US annually is abouta. 500b. 85c. 300d. 345
c
Considering Figure 7.2 on p. 117 of the Uman text, what was the percent decrease in the annual number of lighting deaths between 1920 and 1960?a. 100%b. 78%c. 67%d. 50%
c
During the period 1960-1996, the percentage of lightning injuries that occurred under trees was abouta. 6%b. 18%c. 13%d. 28%
c
According to Holle et al. 2005, Storm Data underestimates the the average number of lightning deaths that have occurred per year during the period 1966-1995 in the US. It is likely that on average the correct number is abouta. 300b. 85c. 200d. 100
d
It appears that whether or not death will result from a lightning strike depends on the energy absorbed by a body. Uman says that a threshold for lethality is probably about 7000 Joules. What are the currents and durations of lightning currents suggested by Uman that can deliver this energy?a. 1000 Amperes for 10 microsecondsb. 100 Amperes for 1 millisecondc. 10 Amperes for 0.1 secondd. all of the above
d
The NFPA recommends protection of trees that are within 3 meters of a structure. Why?a. a side flash might occurb. the tree could catch fire which could spread to the structurec. the tree could exploded. all of the above
d
The state ranked 6 in damage reports per capita over the period 1959-1994 isa. Hawaiib. Washingtonc. Pennsylvaniad. Oklahoma
d
The state ranked highest in fatalities over the period 1959-1994 is a. Hawaiib. Washingtonc. Pennsylvaniad. Florida
d
Lightning without continuing current cannot cause fires.
false
T/F According to Uman, the primary cause of death and injury to humans is damage to the central nervous system.
false
T/F According to Uman, the secondary cause of death and injury to humans caused by lightning is cardiopulmonary arrest.
false
T/F It is unsafe to touch or help individuals who have been struck by lightning.
false
T/F Victims of direct lightning strikes are very soften seriously burned.
false
T/F When inside a building during a lightning storm if you have pvc plumbing it is ok to take a shower, wash hands, do dishes, but contrary to public opinion you should not use cordless phones and cell phones.
false
