Deck 14: Lightning Protection

Question 1

How does lightning restore electrical balance?

Answer 1

The earth has a surplus of electrons and is about 300,000 volts negative with respect to the ionosphere. This means that a person of average height, while standing, is covered from foot to head by a potential gradient of about 260 volts. The typical reaction to this statement is "Why doesn't the person feel a shock?" Electrical shock is measured in terms of current, and the current in this case is infinitesimal. (The air-Earth current is calculated to be between 1400 amperes and 1800 amperes or about 0.000,009 ampere per square mile.) But the total current from Earth is sufficient to upset nature's balance, and lightning is thought to be a natural way of restoring the balance. It is estimated that, on the average, the earth is struck by lightning 100 times per second, and in about 90 percent of these events, electrons flow to the earth. However, there is not full agreement on how this comes about.

Question 2

The air terminal is a solid or tubular rod made of copper, bronze, or ____.

A) silver
B) gold
C) aluminum
D) platinum

Answer 2

C

Question 3

It is estimated that, on average, the earth is struck by lightning 100 times per ____.

A) second
B) minute
C) hour
D) day

Answer 3

A

Question 4

A(n) ____ is the potential energy a charge gains when one joule of work is done on one coulomb.

A) ohm
B) farad
C) ampere
D) volt

Question 5

When conceptualizing lightning and charge distribution, the endpoints to consider are Point B on Earth and Point A in the ____.

A) troposphere
B) ionosphere
C) stratosphere
D) magnetosphere

Question 6

If 6,250,000,000,000,000,000 electrons are transferred from Point A to Point B, the quantity of charge is referred to as a(n) ____ .

A) joule
B) farad
C) coulomb
D) electron-volt

Question 7

The lightning stroke is attracted to the terminal because it is a part of the path that offers the ____ to ground.

A) least impedance
B) most impedance
C) least voltage
D) most voltage

Question 8

What guidelines should you follow when selecting and installing air terminals?

Question 9

Lightning conductors should provide at least ____ paths for current flow from an air terminal to Earth.

A) two
B) three
C) four
D) five

Question 10

Describe the grounding connections in a lightning protection system.

Question 11

Lightning is generated by the ominous-looking ____ cloud or thundercloud.

A) cirrostratus
B) altocumulus
C) cumulonimbus
D) cirrus

Question 12

What is an ion and how is it useful?

Question 13

Lightning protection systems have three basic components: air terminals, lightning conductors, and ____ connections.

A) rod
B) standard
C) safety
D) grounding

Question 14

A single drop of water contains about ____ atoms.

A) 1000
B) 100,000
C) 10 million
D) 100 billion

Question 15

If you are ever present when a person is struck by lightning, immediately ____.

A) move them to the lowest elevation
B) begin CPR
C) call 911
D) find shelter

Question 16

The installation of lightning protection systems for structures in the open should be guided by the requirements of Master Label Service, which is endorsed by ____.

A) UL
B) MET
C) NSF
D) TUV

Question 17

Cloud-to-Earth lightning strokes are most likely to occur ____.

A) in urban areas
B) at a high point
C) in valleys
D) in rural areas

Question 18

Persons struck by lightning carry ____.

A) a high electrical charge that remains for hours
B) a high electrical charge that remains for a few minutes
C) a low electrical charge that remains for a few minutes
D) no electrical charge

Question 19

List five safety rules for human protection when lightning threatens that are recommended by United States Department of Commerce, National Oceanic and Atmospheric Administration.

Question 20

Each atom has at its center a nucleus that is composed of protons and ____.

A) neutrons
B) electrons
C) neutrinos
D) muons