Question

A bicycle generator creates $1.5V$ at $15km/hr$. The $EMF$ generated at $10km/hr$ is

• A. 1.5 volts
• B. 2 volts
• C. 0.5 volts
• D. 1 volts

Answer 1

Answer: (D)

Emf induced, $\epsilon =Blv$
Here, $\bar{B},\bar{l}$ and $\bar{v}$ are mutually perpendicular
For given $B$ and $l,\epsilon \propto v$.
$\therefore \frac{{\epsilon }_1}{{\epsilon }_2}=\frac{v_1}{v_2}$
Here, ${\epsilon }_1=1.5V,v_1=15km/hr=15\times \frac{5}{18}m{s}^{-1}$
$v_2=10km/hr=10\times \frac{5}{8}m{s}^{-1},{\epsilon }_2=?$
So, $\frac{1.5}{{\epsilon }_2}=\frac{15\times \frac{5}{18}}{10\times \frac{5}{18}}=\frac{3}{2};{\epsilon }_2=1V$