Question
Lightning conductors are used to protect buildings from
lightning strikes. Which of the following statements regarding lightning conductors are correct? 1. A lightning conductor creates an electric field at its tip to attract the lightning discharge toward itself. 2. Lightning conductors reduce the effect of the discharge current on the building by safely transferring the electric charge into the ground. 3. The conductivity of the earth is considerably lower than that of the building. 4. Lightning conductors are installed at elevated positions on buildings. Choose the correct answer using the codes given below:Solution
• Lightning conductors (usually made of copper) are installed at the topmost parts of buildings to create an electric field that attracts lightning discharges towards themselves rather than allowing the discharge to strike the building directly. Thus, statement 1 is correct. • These conductors safely carry the electric discharge deep into the earth, preventing damage to the structure. Thus, statement 2 is correct. • However, the conductivity of the earth is higher, not lower, than that of a building material, so statement 3 is incorrect. • Lightning conductors are installed at the highest point on buildings to offer a path of least resistance for the discharge, thus statement 4 is correct. Thus, the correct answer is (c) 1, 3, and 4.
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All Months are Years.
Only a few Years are Weeks.
No Week is Day.
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All music are composers.
Some composers are lyrics.
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Three statements are given followed by three conclusions numbered I, II & III. Assuming the statements to be true, even if they seem to be at variance ...
Statement:Â
Some jeans are not shirt.
All shirts are pant.
Some pants are not blazers.
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I. Some blaze...
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All lion are tiger
No tiger is a cat
No lion is a dog
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I. Some lion are not cat
II. Some tiger are not dog
Read the given statements and conclusions carefully. Assuming that the information given in the statements is true, even if it appears to be at varianc...
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                          All cuckoo are duck.
Conclusions: I. some hawk ...
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I. Some Flats are Buildings.
II. Some Apartments are Flats.
III. No Building is a Roof.
Statements:
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No Addition is a Multiplication.
Some Multiplication are Subtraction.
All Subtraction are Division.
Only few Div...
