Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
NEET 2026
Exam
NEET
Year
2026
Subject
Physics
Chapter
Chapter

NEET 2026 · Physics · Chapter

A uniform nichrome wire of length 4.0\ m and cross-sectional area...

A uniform nichrome wire of length 4.0 m4.0\ \text{m} and cross-sectional area 0.2 mm20.2\ \text{mm}^2 has an electrical resistance of 5.0 Ω5.0\ \Omega. If an electric field of 1.5 V m−11.5\ \text{V m}^{-1} is established along its length, the current density in the wire is:

Options

  1. A1.5×106 A m−21.5 \times 10^6\ \text{A m}^{-2}
  2. B6×104 A m−26 \times 10^4\ \text{A m}^{-2}
  3. C6×106 A m−26 \times 10^6\ \text{A m}^{-2}
  4. D2.4×10−7 A m−22.4 \times 10^{-7}\ \text{A m}^{-2}

Correct answer

C. 6×106 A m−26 \times 10^6\ \text{A m}^{-2}

Step-by-step solution

Given l=4.0 ml = 4.0\ \text{m}, A=0.2 mm2=2×10−7 m2A = 0.2\ \text{mm}^2 = 2 \times 10^{-7}\ \text{m}^2, R=5.0 ΩR = 5.0\ \Omega, and E=1.5 V m−1E = 1.5\ \text{V m}^{-1}.

The potential difference across the wire is:

V=E×l=1.5×4.0=6.0 VV = E \times l = 1.5 \times 4.0 = 6.0\ \text{V}

The current flowing through the wire is:

I=VR=6.05.0=1.2 AI = \dfrac{V}{R} = \dfrac{6.0}{5.0} = 1.2\ \text{A}

The current density JJ is given by:

J=IA=1.22×10−7=6×106 A m−2J = \dfrac{I}{A} = \dfrac{1.2}{2 \times 10^{-7}} = 6 \times 10^6\ \text{A m}^{-2}

Answer: 6×106 A m−26 \times 10^6\ \text{A m}^{-2}
Practice Chapter on Quantrex Academy →

More from Chapter

A solid spherical body of radius R , density ρ , and specific heat capacity s is… NEET 2026A straight canal has motorboats departing from two terminals at opposite ends. The… NEET 2026A wooden crate is released from rest at the top of a ramp inclined at 37^ ∘ to the… NEET 2026A uniform horizontal beam of mass 6 kg and length L is hinged to a vertical wall at one… NEET 2026A bullet P of mass 30 g moving with a speed of 200 m/s penetrates a target and comes to… NEET 2026A small block of mass m is placed at the highest point of a smooth fixed sphere of radius… NEET 2026A block of mass 2 kg is projected with an initial speed of 14 m/s on a rough horizontal… NEET 2026A uniform horizontal circular disc of mass M and radius R is rotating freely about a… NEET 2026 Full Chapter list All NEET PYQs