JEE Mains · Physics · STD 12 - Current electricity
- JEE Mains 2015
- Medium
- MCQ
When \(5\ V\) potential difference is applied across a wire of length \(0.1\ m\), the drift speed of electrons is \(2.5 \times 10^{-4}\) \(ms^{-1}\) . If the electron density in the wire is \(8 \times 10^{28}\) \(m^{-3}\) the resistivity of the material is close to
Pick an option to check your answer.
Answer & Solution
Correct Answer
(B) \(1.6 \times 10^{-5} \) \(Ω m\)
Step-by-step Solution
Detailed explanation
\(V=I R=\left(n e A v_{d}\right) \rho \frac{\ell}{A}\)
\(\therefore \quad \rho=\frac{\mathrm{V}}{\mathrm{V}_{\mathrm{d}} \mathrm{lne}}\)
Here \(\mathrm{V}=\) potential difference
\(\mathrm{I}=\) length of wire
\(\mathrm{n}=\mathrm{no} .\) of electrons per unit volume of conductor.
\(\mathrm{e}=\mathrm{no.}\) of electrons
Placing the value of above parameters we get resistivity
\(\rho=\frac{5}{8 \times 10^{28} \times 1.6 \times 10^{-19} \times 2.5 \times 10^{-4} \times 0.1}\)
\(=1.6 \times 10^{-5} \,\Omega m\)
More questions from Physics
- The equation of motion of a particle is given by \(x = a \sin\left(50t + \dfrac{\pi}{3}\right)\) cm. The particle will come to rest at time \(t_1\) and it will have zero acceleration at time \(t_2\). The \(t_1\) and \(t_2\) respectively are _______.JEE Mains 2026 Medium
- The velocity of a small ball of mass ' \(m\) ' and density \(d _{1}\), when dropped in a container filled with glycerine, becomes constant after some time. If the density of glycerine is \(d _{2}\), then the viscous force acting on the ball, will beJEE Mains 2022 Medium
- A plane electromagnetic wave propagates along the \(+x\) direction in free space. The components of the electric field, \(\vec{E}\) and magnetic field, \(\vec{B}\) vectors associated with the wave in Cartesian frame areJEE Mains 2025 Easy
- Given below are two statements: one is labelled as Assertion\((A)\) and the other is labelled as Reason \((R).\) \(Assertion\) \((A)\) : In Vernier calliper if positive zero error exists, then while taking measurements, the reading taken will be more than the actual reading. \(Reason\) \((R)\) : The zero error in Vernier Calliper might have happened due to manufacturing defect or due to rough handling. In the light of the above statements, choose the correct answer from the options given below :JEE Mains 2024 Hard
- At some instant, a radioactive sample \(S_1\) having an activity \(5\,\mu Ci\) has twice the number of nuclei as another sample \(S_2\) which has an activity of \(10\,\mu Ci.\) The halflives of \(S_1\) and \(S_2\) areJEE Mains 2018 Hard
- A motor operating on 100 V draws a current of 1 A. If the efficiency of the motor is \(91.6 \%\), then the loss of power in units of \(\mathrm{cal} / \mathrm{s}\) is _________.JEE Mains 2025 Medium
More PYQs from JEE Mains
- The diameter of a wire measured by a screw gauge of least count \(0.001\) cm is \(0.08\) cm. The length measured by a scale of least count \(0.1\) cm is \(150\) cm. When a weight of \(100\) N is applied to the wire, the extension in length is \(0.5\) cm, measured by a micrometer of least count \(0.001\) cm. The error in the measured Young's modulus is \(\alpha \times 10^9\) N/m\(^2\). The value of \(\alpha\) is _______.
(Ignore the contribution of the load to Young's modulus error calculation)JEE Mains 2026 Hard - The angular width of the central maximum in a single slit diffraction pattern is \(60^o \) . The width of the slit is \(1\ \mu m\). The slit is illuminated by monochromatic plane waves. If another slit of same width is made near it, Young's fringes can be observed on a screen placed at distance \(50\ cm\) from the slits. If the observed fringe width is \(1\ cm\), what is slit separation distance?.........\(\mu m\)
(i.e. distance between the centres of each slit. )JEE Mains 2018 Medium