JEE Main 2022 — Physics Electromagnetism

2022integerhard

A $1m$ long copper wire carries a current of $1A$ . If the cross section of the wire is $2.0{\mathrm{mm}}^{2}$ and the resistivity of copper is $1.7\times {10}^{-8}\Omega m$ . The force experienced by moving electron in the wire is _____ $\times {10}^{-23}N$

(Charge of electron $=1.6\times {10}^{-19}C$ )

Official previous-year question

Held on 27 Jul 2022 · Verified 6 Jul 2026.

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Solution

Given here, length $l=1m$ , current $i=1A$ , area $A=2\times {10}^{-6}m$ and resistivity $\rho =1.7\times {10}^{-8}\Omega m$ .

Resistance of wire is $R=\frac{\rho l}{A}=\frac{1.7\times {10}^{-8}\times 1}{2\times {10}^{-5}}=\frac{1.7}{2}\times {10}^{-2}\Omega$

Now, electric field in the wire is $E=\rho J$ , where, $J=\frac{i}{A}$ is current density.

Thus, $E=\frac{i\rho }{A}=iR=1\times \frac{1.7}{2}\times {10}^{-2}V{m}^{-1}$

Electric force in terms of electric field is given by $F=qE$

Therefore, force experienced by moving electron is $F=1.6\times {10}^{-19}\times \frac{1.7}{2}\times {10}^{-2}$

$=1.36\times {10}^{-21}$ $=136\times {10}^{-23}N$

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JEE Main 2022 — Physics Electromagnetism

2022integerhard

(Charge of electron $=1.6\times {10}^{-19}C$ )

Official previous-year question

Held on 27 Jul 2022 · Verified 6 Jul 2026.

Did you get this right?

Solution

Given here, length $l=1m$ , current $i=1A$ , area $A=2\times {10}^{-6}m$ and resistivity $\rho =1.7\times {10}^{-8}\Omega m$ .

Resistance of wire is $R=\frac{\rho l}{A}=\frac{1.7\times {10}^{-8}\times 1}{2\times {10}^{-5}}=\frac{1.7}{2}\times {10}^{-2}\Omega$

Now, electric field in the wire is $E=\rho J$ , where, $J=\frac{i}{A}$ is current density.

Thus, $E=\frac{i\rho }{A}=iR=1\times \frac{1.7}{2}\times {10}^{-2}V{m}^{-1}$

Electric force in terms of electric field is given by $F=qE$

Therefore, force experienced by moving electron is $F=1.6\times {10}^{-19}\times \frac{1.7}{2}\times {10}^{-2}$

$=1.36\times {10}^{-21}$ $=136\times {10}^{-23}N$

Your note

JEE Main Electromagnetism in other years

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Work through every JEE Main Electromagnetism PYQ, year by year.

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JEE Main 2022 — Physics Electromagnetism

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Solution

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JEE Main 2022 — Physics Electromagnetism

Did you get this right?

Solution

Your note

JEE Main Electromagnetism in other years

More JEE Main Electromagnetism questions

Other Physics topics for JEE Main

Mechanics

Modern Physics

Optics

Thermodynamics

Waves & Oscillations

Keep practicing Electromagnetism