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.
Select the most appropriate indirect form of the given sentence.
I said to my friend, “Please help me arrange these books on the shelf.”
Select the correct indirect form of the given sentence.
You said to me, “I slept well last night.”
My father said to me, "Don't talk to your mother like that."
Sumit said, “I will be leaving for London this summer so I can meet you only when I return.”
Manoj said to his friend, "I am very angry with you."
Select the option that expresses the given sentence in reported speech.
Raghav said to Meera, “Are you upset with me?”
Ram said,"Are you really serious about becoming a pilot, son?"
"Well ,well," He said. "A strange man!"
Select the most appropriate indirect/direct form of the given sentence.
The teacher said, “The class has been scheduled for tomorrow.”
The speeding car knocked down the pedestrian.
