Hot questions

Define emf. of a cell? On what factors does it depend?
Answer : ### Definition of EMF (Electromotive Force) The **EMF (Electromotive Force)** of a cell is defined as the maximum potential difference between its two terminals when no current is being drawn ... *, not its EMF. A larger distance increases the path ions must travel, increasing internal resistance....

Three identical cells, each of emf. 2V and unknown internal resistance are connected in parallel. This combination is connected to a 5 ohm resistor. If the terminal voltage across the cell is 1.5 volt. What is the internal resistance of each cell? Hence define the internal resistance of a cell?
Answer : ### Part 1: Calculating the Internal Resistance Here's how we can find the internal resistance of each cell. **Given Data:** * Electromotive force (EMF) of each cell, E = 2 V * Number of identical cells ... . * **I** is the current flowing from the cell. * **r** is the internal resistance....

State two insulators of following types along with their areas of application: (i) Class A (ii) Class E (iii) Class H
Answer : Here are two examples of insulating materials for each specified class, along with their areas of application. These insulation classes are defined by their maximum allowable operating temperature, ... traction motors (used in trains), which operate under severe thermal and mechanical stress....

A high tension (HT) supply of, say, 6 kV must have a very large internal resistance. Why?
Answer : The primary reason is **safety and current limiting**. Let's use Ohm's Law ($V = IR$) to understand this. A power supply can be modeled as an ideal voltage source ($V_s$) in series ... HT supply for **power transmission** has a very low internal resistance for **efficiency and power delivery**....

Compare the electrical, mechanical and thermal properties of : i) asbestos (ii) mica (iii) porcelain as an insulating material
Answer : ### Classification of Wiring Electrical wiring can be classified based on several criteria, but for installation purposes, it is most commonly classified by the **method of installation and ... is essential for managing the complex electrical needs of kitchens, laundries, and HVAC systems....

Explain with justification two uses of each of two following as an electrical conductor: (i) Brass (ii) Silver
Answer : ### (i) Brass Brass is an alloy primarily made of copper and zinc. While it is a good electrical conductor, it is not as conductive as pure copper. Its usefulness comes from a ... silver (lowest possible signal loss) while keeping the cost much lower than using a solid silver conductor....

A cylindrical wire is stretched to increase its length by 10% calculate the percentage increase in resistance?
Answer : The percentage increase in resistance is **21%**. Here is the step-by-step calculation and explanation: ### The Key Concepts 1. **Resistance Formula:** The resistance (R) of a wire is given by: $R = \ ... R_1}{R_1} \times 100\%$ $\text{Percentage Increase} = 0.21 \times 100\% = \bf{21\%}$...

Compare the casing / capping system of electrical wiring to concealed system of electrical wiring. On the basis of look, cost, life, safety retentivity of material and suitability for locations.
Answer : This comparison covers two of the most common methods for electrical wiring in buildings. Here is a detailed comparison of the Casing/Capping system and the Concealed Conduit system based on your ... and safety to the property. It is the standard for modern residential and commercial construction....

State the need for strictly following safety rules while working in electrical installations.
Answer : Strictly following safety rules while working in electrical installations is not merely a recommendation; it is an absolute necessity. Electricity is an invisible, powerful, and unforgiving hazard. The rules ... protect the worker, their colleagues, the public, and the property they are working on....

Describe with reasons the failure of porcelain insulators.
Answer : ### **Introduction: The Role of Porcelain Insulators** Porcelain insulators are a critical component in electrical power systems. Their primary functions are twofold: 1. **Electrical Insulation: ... , and maintenance strategies (like insulator washing) to ensure the reliability of the power grid....