Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
JEE Main202312 Apr 2023Morning ShiftPhysicsCurrent ElectricityActual

A wire of resistance 160 Ω is melted and drawn in a wire of one-fourth of its length. The new resistance of the wire will be

Options

  1. A16   Ω
  2. B10   Ω
  3. C640   Ω
  4. D40   Ω

Correct answer

B. 10   Ω

Step-by-step solution

The formula to calculate the resistance of the original wire is given by R = ρ l A       . . . 1 When the new wire is formed, its resistance is given by R ' = ρ l ' 4 A       . . . 2 Divide equation (2) by equation (1) and simplify to obtain the expression for the new resistance. R ' R = ρ l ' 4 A ρ l A ⇒ R ' = R l ' 4 l       . . . 3 Substitute the values of the known parameters into equation (3) to calculate the require

Practice Current Electricity on Quantrex Academy →

More from Current Electricity

A metal wire of cross-sectional area 0.5 mm ^2 and length 100 m is connected across a battery of e.m.f. 2 V and internal resistance 1 . The density, atomic mass and electrical cond 2026As shown in the figure, the resistance of a galvanometer G can be found by the half-deflection method. Here the resistance R₂ is adjusted such that when the key K is closed the def 2026The stored charge in the capacitor in steady state of the following circuit is ________ C. 2026A moving coil of galvanometer when shunted with 2 , resistance gives a full scale deflection for a current of 500 mA. When a resistance of 470 , is connected in series it gives a f 2026Two cells of emfs 1 V and 2 V and internal resistance 2 , and 1 , , respectively connected in parallel, gave a current of 1 A through an external resistance. If the polarity of one 2026Refer to the circuit diagram given below. The heat generated across the 6 , resistance in 100 second is 100 J. The value of is _______. (Nearest integer) 2026In an experiment to determine the resistance of a given wire using Ohm's law, the voltmeter and ammeter readings are noted as 10 V and 5 A , respectively. The least counts of voltm 2026Under steady state condition the potential difference across the capacitor in the circuit is _______ V. 2026 Full Current Electricity list All JEE Main PYQs