The grinder is designed to operate at an input voltage of $V_{in} = 220\text{ V}$. The available power supply in the U.S. is $V_{source} = 110\text{ V}$. Since the device requires a higher voltage than what is available, we must increase the voltage.
To increase the voltage from $110\text{ V}$ to $220\text{ V}$, a step-up transformer is required.
The transformer equation is given by: $$ \frac{V_s}{V_p} = \frac{N_s}{N_p} $$ Where $V_s$ is the secondary voltage ($220\text{ V}$) and $V_p$ is the primary voltage ($110\text{ V}$). $$ \frac{N_s}{N_p} = \frac{220}{110} = \frac{2}{1} $$ Wait, checking the options: The ratio $N_p : N_s$ is $1 : 2$. Thus, a step-up transformer with a turn ratio of $1 : 2$ is required.
Final Answer: C
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