Hot questions

Two electric bulbs A and B are marked 220V , 40W and 220V 60W respectively. Which one has a higher resistance?
Answer : **The 40W bulb (Bulb A) has a higher resistance.** Here's the detailed explanation of why: ### The Relationship The relationship between Power (P), Voltage (V), and Resistance (R) is given by ... to get more water through a pipe; you need a wider pipe (less resistance) to increase the flow rate....

A battery of emf E and internal resistance r sends a current, I1 , I2 when connected to an external resistance of R1 , R2 respectively. Find the emf. and internal resistance of the battery.
Answer : Let's derive the expressions for the electromotive force (EMF) and the internal resistance of the battery step-by-step. ### Understanding the Setup The core principle we'll use is Ohm's law applied to the entire circuit. For a ... $$ **EMF (E):** $$ E = \frac{I_1 I_2 (R_1 - R_2)}{I_2 - I_1} $$...

Why is constantan or manganin used for making standard resistors?
Answer : Constantan and manganin are used for making standard resistors for a specific combination of four key properties that make them ideal for precision applications. Here's a breakdown of why these alloys ... precision and stability required in a metrology lab, **manganin is the preferred material.**...

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....

State and explain Kirchhoff’s law?
Answer : Kirchhoff's laws are two fundamental principles used to analyze electric circuits. They were formulated by Gustav Kirchhoff in 1845 and are based on the conservation of charge ... =blob&qa_blobid=16131873694589351449 [2]: https://electrical-engineering.app/?qa=blob&qa_blobid=10917265924274549047...

A Carbon resistor has three strips of red colour and a gold strip. What is the value of the resistor? What is its tolerance?
Answer : The value of a carbon resistor is determined by the standard resistor color code system. For a 4-band resistor: * **Band 1:** First significant digit * **Band 2:** Second significant ... a new resistor with these color bands will have an actual resistance somewhere between 2090 Ω and 2310 Ω....

What happens to the resistance of the wire when its length is increased to twice its original length?
Answer : This gets to the core of how resistance works. The short and direct answer is: **The resistance of the wire will double.** Here's a more detailed explanation of why. ### 1. The Simple Explanation (Analogy) Think of the wire ... (x2) | Halves (x0.5) | **Quadruples (x4)** |...

Why do we prefer a potentiometer to measure the emf of a cell rather than a voltmeter?
Answer : The primary reason we prefer a potentiometer to measure the EMF of a cell is that **a potentiometer draws no current from the cell at the point of measurement.** A voltmeter, by its ... method ensures no current is drawn, thereby eliminating any error caused by the source's internal resistance....

With suitable circuit diagram, show how emfs of 2 cells can be compared using a potentiometer?
Answer : ![][1] [1]: https://electrical-engineering.app/?qa=blob&qa_blobid=16022041933233000659 ### **Principle of a Potentiometer** A potentiometer works on the principle that the potential drop ... -section. 4. The current in the primary circuit should be kept constant throughout the experiment....

State significance of earthing. Draw and explain pipe earthing. State the values of earth resistances for : (i) Substation (ii) Residential wiring (iii) H.T. Line (iv) L.T. Line
Answer : ### 1. Significance of Earthing Earthing (or grounding) is a fundamental safety measure in any electrical installation. Its primary significance is to protect people, equipment, and property from ... to consumers. [1]: https://electrical-engineering.app/?qa=blob&qa_blobid=3390146307772186646...