Hot questions

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....

Explain the phenomenon of loss of magnetism.
Answer : ### The Short Answer Loss of magnetism, also known as **demagnetization**, is the process where a magnetic material loses its magnetic properties. This happens when the microscopic "mini-magnets" inside the material, ... 's own stray field. | A structure slowly eroding due to wind and rain. |...

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....

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....

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: $R = \ ... R_1}{R_1} \times 100\%$ $\text{Percentage Increase} = 0.21 \times 100\% = \bf{21\%}$...

Obtain ohm’s law from the expression for electrical conductivity.
Answer : We can derive the familiar form of Ohm's Law ($V=IR$) by starting with the fundamental expression for electrical conductivity ($\sigma$). This derivation beautifully connects the microscopic behavior of ... total **current ($I$)** flowing through it, successfully obtaining Ohm's Law, $V=IR$....

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....

Two wires A and B are of the same metal and of same length have their areas of cross section in the ratio 2:1 if the same potential difference is applied across each wire in turn, what will be the ratio of current flowing in A & B ?
Answer : The ratio of the current flowing in wire A to wire B is **2:1**. --- ### Detailed Explanation Let's break down the problem using the relevant physics principles. #### 1. List the Given ... resistance, which is wire A. Our result confirms this: the current in A is twice the current in B....

Given n resistors each of resistance R, how will you combine them to get the (i) maximum (ii) minimum effective resistance? What is the ratio of the maximum to minimum resistance?
Answer : The two fundamental ways to combine resistors are in **series** and in **parallel**. These two configurations yield the maximum and minimum possible resistances, respectively. --- ### (i) Maximum Effective Resistance To obtain the * ... {min} = R/n$ | | **Ratio** | $R_{max} / R_{min}$ | $n^2$ |...

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....