
A ring is made of a wire having a resistance of \(R_0=12~\Omega.\). Find points \(\mathrm{A}\) and \(\mathrm{B}\), as shown in the figure, at which a current-carrying conductor should be connected so that the resistance \(R\) of the subcircuit between these points equals \(\frac{8}{3}~\Omega\)

| 1. | \(\dfrac{l_1}{l_2} = \dfrac{5}{8}\) | 2. | \(\dfrac{l_1}{l_2} = \dfrac{1}{3}\) |
| 3. | \(\dfrac{l_1}{l_2} = \dfrac{3}{8}\) | 4. | \(\dfrac{l_1}{l_2} = \dfrac{1}{2}\) |
A wire of resistance \(12~ \Omega \text{m}^{-1}\) is bent to form a complete circle of radius \(10~\text{cm}\). The resistance between its two diametrically opposite points, \(A\) and \(B\) as shown in the figure, is:

| 1. | \(0.6\pi~\Omega\) | 2. | \(3\pi ~\Omega\) |
| 3. | \(61 \pi~ \Omega\) | 4. | \(6\pi~\Omega\) |
1. 1.2 times, 1.1 times
2. 1.21 times, same
3. both remain the same
4. 1.1 times, 1.1 times
1. 1.5 V
2. 1.0 V
3. 0.5 V
4. 3.2 V
When a wire of uniform cross-section a, length l, and resistance R is bent into a complete circle, the resistance between any two diametrically opposite points will be:
1. R/2
2. R/4
3. R/8
4. 4R
The electric resistance of a particular wire of iron is \(R.\) If its length and radius are doubled, then:
| 1. | the resistance will be halved and the specific resistance will remain unchanged |
| 2. | the resistance will be halved and the specific resistance will be doubled |
| 3. | the resistance and the specific resistance will both remain unchanged |
| 4. | the resistance will be doubled and the specific resistance will be halved |
Resistances \(n,\) each of \(r~\text{ohm},\) when connected in parallel give an equivalent resistance of \(R~\text{ohm}.\) If these resistances were connected in series, the combination would have resistance in \(\text{ohms}\) equal to:
1. \(\dfrac{R}{n^2}\)
2. \(\dfrac{R}{n}\)
3. \(nR\)
4. \(n^2R\)