Question

Vinay was given a circle constructed of a uniform wire of resistance of $2$ ohm per cm by his teacher. She asked him to connect it in a circuit such that it offers maximum resistance. Find the maximum resistance(Take radius of the circle as 7 cm)

• A. $44\Omega$
• B. $22\Omega$
• C. $88\Omega$
• D. $11$ $\Omega$

Answer 1

The correct option is C $88\Omega$

Given resistance = 2$\Omega$/cm

a wire has same cross section,so we can say that $R\propto l$

For 1 cm, resistance=2$\Omega$

$2\times \pi rcm$,resistance$=2\times 2\times \pi \times r=2\times 2\times \frac{22}{7}\times 7=88\Omega$