Question

A metal bar of length 1 metre falls from rest under gravity while remaining horizontal with its ends pointing toward magnetic east west. What is the potential difference when it has fallen 10 metres? Horizontal component of earth's field is ${1.7\times 10}^{-5}$ Tesla

• A. 0.238 mV
• B. 1 mV
• C. 0.5 nV
• D. 0.75 mV

Answer 1

The correct option is B 1 mV

A metal bar of length $=1m$ gravity while remaining horizontal with its end point toward magnetic east west potential difference fallen $=10m$

Electric field $=1.7\times {10}^{-5}T$

Using Hall effect $=e=Blv=1.7\times {10}^{-5}\times 10\times 1=1mV$