Recent questions in Physics

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** | $R_{max} / R_{min}$ | $n^2$ |...

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**....

A low voltage supply from which one needs high currents must have very low internal resistance. Why?
Answer : ### The Simple Analogy: A Water Pipe Imagine your power supply is a large water tank (representing the voltage) and you need to get a high flow of water (high current) out of a pipe at ... extremely small, this will generate a massive amount of heat, which can damage or destroy the power supply....

Is ohm’s law universally applicable for all conducting elements? If not, give examples of elements which do not obey Ohm’s law.
Answer : The answer is no, **Ohm's law is not universally applicable for all conducting elements.** Ohm's law is an empirical rule, not a fundamental law of nature. It accurately describes the ... under stable conditions, but it is far from a universal law for all materials that conduct electricity....

A steady current flow in a metallic conductor of non-uniform crosssection. Which of these quantities is constant along the conductor: current, current density, electric field, drift speed?
Answer : Here is a detailed explanation for each quantity: ### 1. Current (I) * **Why it's constant:** The term "steady current" implies that the rate of flow of charge ($I = dQ/dt$) is constant. Due to the ... ($v_d$)** | Not Constant | $v_d = I/(nAe)$. Since A is not constant, $v_d$ is not constant. |...