When Two Resistors of Resistances $R _ { 1 }$ And $R _ { 2 }$

Multiple Choice

When two resistors of resistances $R _ { 1 }$ and $R _ { 2 }$ are connected in parallel (see figure) , the total resistance $R$ satisfies the equation $$\frac { 1 } { R } = \frac { 1 } { R _ { 1 } } + \frac { 1 } { R _ { 2 } }$$ . Find $R _ { 1 }$ for a parallel circuit in which $R _ { 2 } = 7$ ohms and R must be at least 1 ohm.

A) $R _ { 1 } \leq 7 \text { ohms }$
B) $R _ { 1 } < 7 \text { ohms }$
C) $R _ { 1 } \geq$ $\frac { 7 } { 6 }$ $\text { ohms }$
D) $R _ { 1 } > 7 \mathrm { ohms }$
E) $R _ { 1 } =$ $\frac { 7 } { 6 }$ $\text { ohms }$