A 20 m long uniform copper wire held horizontally is allowed to fall under the gravity (g=10 ~m / s^2) through a uniform horizontal magnetic field of…
JEE Main 2026 — Physics Electromagnetism
2026mcqmedium
A 20 m long uniform copper wire held horizontally is allowed to fall under the gravity (g=10m/s2) through a uniform horizontal magnetic field of 0.5 Gauss perpendicular to the length of the wire. The induced EMF across the wire when it travells a vertical distance of 200 m is ____ mV.
Official previous-year question
Held on 23 Jan 2026 · Verified 6 Jul 2026.
Options
A
2010
B
0.210
C
20010
D
210
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Solution
For a conducting wire falling in a magnetic field, induced EMF is: E=BLv
After falling through height h=200 m, velocity: v=2gh=2×10×200=4000=2010 m/s
Converting magnetic field: B=0.5 Gauss =0.5×10−4 T
Induced EMF: E=(0.5×10−4)×20×2010=200×10−410=0.0210 V =2010 mV
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