Question

What is the largest voltage the battery can have without breaking the circuit at the supports?

• A. 817 V
• B. 412 V
• C. 325 V
• D. 160 V

Answer 1

The correct option is A 817 V

The maximum magnetic force on the bar will balance the weight of the bar.
$\therefore F_m=mg$

$\therefore ilB=mg$
$\therefore \frac{V}{R}lB=mg$

$\Rightarrow V=\frac{mgR}{lB}=\frac{0.75\times 9.8\times 25}{50\times {10}^{-2}\times 0.45}=817V$