Identical resistances, of value \(R\), each, are connected along the edges of a tetrahedron. If the equivalent resistance of this combination is measured between two vertices, it will be:
| 1. | \(\dfrac{R}{2}\) | 2. | \(\dfrac{R}{4}\) |
| 3. | \(\dfrac{R}{6}\) | 4. | \(2R\) |

| 1. | \(1~\text{A}\) | 2. | \(\dfrac{7}{6} ~\text{A}\) |
| 3. | \(\dfrac{5}{6} ~\text{A}\) | 4. | \(\dfrac{1}{2}~\text{A}\) |
A straight wire of resistance \(R\) is shaped into the form of an equilateral triangle and its ends joined. The resistance of this triangle between the two vertices is:
| 1. | \(\dfrac{R}{3}\) | 2. | \(\dfrac{R}{9}\) |
| 3. | \(\dfrac{2R}{9}\) | 4. | \(\dfrac{2R}{3}\) |
The resistivity of a wire changes gradually, linearly along the length — from \(\rho_0\) to \(2\rho_0\). The total length of the wire is \(l\), while its cross-section is \(A\). The total resistance of the wire is:
| 1. | \(\dfrac{\rho_0 l}{A} \ln 2\) | 2. | \(\dfrac{\rho_0 l}{2A} \ln 2\) |
| 3. | \(\dfrac{3 \rho_{0} l}{A}\) | 4. | \(\dfrac{3}{2} {\dfrac{\rho_0l}{A}}\) |

| Assertion (A): | The fractional error in \(R\) is most affected by that of the smallest resistance in the combination, other things being equal. |
| Reason (R): | In parallel, the conductances add. The contribution to the overall error in the conductance is largest for the largest conductance or the smallest resistance. |
| 1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
| 3. | (A) is True but (R) is False. |
| 4. | (A) is False but (R) is True. |
| 1. | \(100~\Omega\) | 2. | \(50~\Omega\) |
| 3. | \(200~\Omega\) | 4. | \(400~\Omega\) |
| 1. | \(\dfrac31\) | 2. | \(\dfrac21\) |
| 3. | \(\dfrac11\) | 4. | \(\dfrac53\) |

| 1. | increases by \(1\) V |
| 2. | decreases by \(1\) V |
| 3. | increases by \(3\) V |
| 4. | decreases by \(3\) V |