Lightening conductors are used to protect building from lightning strikes. Which of the following statements is/are true about lightening conductors? 1) Lightening conductors create an electric field at its top that lightning strikes it preferentially 2) Lightning conductors reduce the effect of the strike by uniformly distributing the charge (current) over the surface of the building 3) Lightning conductors take all the charge (current) to deep down in the earth 4) Lightning conductors must be installed at a place taller than the building
3 and 4 only
Understanding Lightning Conductors and Building Protection
Lightning conductors are essential devices designed to protect buildings and structures from the damaging effects of lightning strikes. They provide a safe path for the massive electrical current from a lightning strike to travel into the ground, preventing the current from flowing through the building itself, which could cause fires, structural damage, or harm occupants.
Analyzing Statements about Lightning Conductors
Let's evaluate each statement regarding lightning conductors:
- Statement 1: Lightening conductors create an electric field at its top that lightning strikes it preferentially.
This statement is partially misleading. While the sharp point of a lightning rod can enhance the local electric field and potentially initiate an upward discharge that intercepts a downward lightning leader, it does not "create an electric field that lightning strikes it preferentially" in the sense of attracting strikes from a vast area. Its primary role is to act as the highest point and provide a low-resistance path *if* a strike is imminent or occurs nearby within its protection zone.
- Statement 2: Lightning conductors reduce the effect of the strike by uniformly distributing the charge (current) over the surface of the building.
This statement is incorrect. The purpose of a lightning conductor is precisely the opposite – to prevent the charge/current from distributing over the surface of the building. Instead, it channels the vast majority of the lightning current safely through the conductor and into the earth, bypassing the building's structure.
- Statement 3: Lightning conductors take all the charge (current) to deep down in the earth.
This statement is largely true. The lightning conductor system includes a rod or network of conductors on the structure, down conductors running along the side, and a grounding system buried deep in the earth. This system provides a low-resistance path for the enormous electrical current from a lightning strike to be safely dissipated into the ground.
- Statement 4: Lightning conductors must be installed at a place taller than the building.
This statement is true. For a lightning conductor to effectively intercept a potential lightning strike within its protected area, it must be the highest point on or immediately adjacent to the structure it is protecting. This ensures that it is the most likely point for a strike to terminate on the building.
Summary of Statements
Based on the analysis:
- Statement 1: Partially true concept (enhancing field/intercepting) but misleading phrasing ("preferentially strikes").
- Statement 2: False. The goal is to avoid distributing charge over the building.
- Statement 3: True. The system channels current to the earth.
- Statement 4: True. It must be the highest point for effective protection.
Therefore, statements 3 and 4 are true regarding the function and installation of lightning conductors.
Revision Table: Lightning Conductor Functions
| Statement | Accuracy | Explanation |
|---|---|---|
| Creates electric field to attract strikes preferentially | Misleading | Enhances local field, intercepts nearby strikes, doesn't attract from far away. |
| Distributes charge over building surface | False | Channels charge away from the building. |
| Takes charge deep into the earth | True | Provides low-resistance path to ground. |
| Installed taller than the building | True | Ensures it is the primary point of contact for strikes. |
Additional Information: How Lightning Protection Works
A complete lightning protection system typically consists of several components:
- Air Terminal (Lightning Rod): The pointed or rounded metal rod(s) at the highest point of the structure, designed to intercept the lightning strike.
- Down Conductors: Heavy cables connecting the air terminal to the grounding system, providing a low-resistance path for the current.
- Grounding Electrode System: One or more metal rods or plates buried in the earth, which safely dissipates the massive electrical energy into the ground. Proper grounding is crucial for the system's effectiveness.
- Bonding: Connecting various metallic parts of the building (like pipes or structural steel) to the lightning protection system to prevent side flashes.
The principle relies on providing a path of least resistance for the lightning current, preventing it from passing through the building's structure, which has much higher resistance and would generate significant heat and potential damage.
Similar Questions
Why are the tyres of aircrafts made of conducting rubber?
1. So that the charge accumulated on the aircraft in flight, by rubbing the air, can easily be transferred to ground on landing.
2. So that the charge accumulated due to the operation of various electronic equipments in the aircraft in flight can easily be transferred to ground on landing.
Select the correct answer using the code given below.A positive charge is moving towards south in a space where magnetic field is pointing in the north direction. The moving charge will experience :
When you walk on a woolen carpet and bring your finger near the metallic handle of a door an electric shock is produced.
This is becauseWhich of the following are the properties of an electron?
1) Electron is a constituent of cathode ray
2) Electron is a negatively charged particle
3) The mass of the electron is equal to the mass of the proton
4) Electron is deflected by the electric field but not by magnetic field
Select the correct answer using the code given below:Two point charges of 4 C and 16 C are kept at a distance of 0.18 m. A third point charge of 1 C is kept between them such that the potential energy of the system is minimum. What is the magnitude of the electric field at the location of the 1 C charge?
Important Questions from Electric Charge
Which of the following expressions correctly represents the SI unit of electric charge, the Coulomb ($C$), in terms of other fundamental or derived SI units?
- Suppose every second 1016 electrons come out of a body and move to another body, then the time is required to get a total charge of 3.2 C on the other body is:
- An object is found to have a net negative charge of $-5 \text{ nC}$. How many excess electrons are present on the object? (Given: elementary charge $e = 1.6 \times 10^{-19} \text{ C}$)
- A metallic sphere, initially possessing a positive electric potential relative to the Earth, is connected to the Earth by a conducting wire. Which of the following accurately describes the primary charge movement that occurs until equilibrium is reached?
Two point charges, $Q_1 = +3 \mu C$ and $Q_2 = -8 \mu C$, are placed at a certain distance apart. They attract each other with a force of $48 N$. If each charge is given an additional charge of $+6 \mu C$, what will be the magnitude and nature of the new force between them?
