| 1. | case (I) but not in case (II). |
| 2. | case (II) but not in case (I). |
| 3. | both cases (I) and (II). |
| 4. | neither of cases (I) and (II). |
| 1. | \(B = \dfrac{mg}{qv}\) | 2. | \(B \leq \dfrac{m g}{q v}\) |
| 3. | \(B \geq \dfrac{m g}{q v}\) | 4. | \(B = \dfrac{qv}{mg}\) |
| 1. | \(\dfrac{\mu_{0} I}{6}\) | 2. | \(\dfrac{2 \mu_{0} I}{6}\) |
| 3. | \(\dfrac{4\mu_{0} I}{6}\) | 4. | \(\dfrac{5\mu_{0} I}{6}\) |
| 1. | \(q^{2}\) | 2. | \(B^{2}\) |
| 3. | \(r^{2}\) | 4. | All of the above |
| 1. | \(OP=R\) | 2. | \(OP=\dfrac R2\) |
| 3. | \(OP=\sqrt3R \) | 4. | \(OP=8R\) |
| 1. | \(\dfrac{\mu_0i}{4r}\) |
| 2. | \(\dfrac{\mu_0i}{4r}+\dfrac{\mu_0i}{2\pi r}\) |
| 3. | \(\dfrac{\mu_0i}{4r}+\dfrac{\mu_0i}{4\pi r}\) |
| 4. | \(\left[\left(\dfrac{\mu_0i}{4r}\right)^2+\left(\dfrac{\mu_0i}{4\pi r}\right)^2\right]^{\frac12} \) |
| 1. | \(\lambda Br\) | 2. | \(\dfrac{\lambda Br}{r}\) |
| 3. | \(\dfrac{\lambda}{Br}\) | 4. | \(\dfrac{\lambda}{B^2r^2}\) |
| 1. | \(6.28 \times 10^{-4} ~\text{T} \) | 2. | \(6.28 \times 10^{-2}~\text{T}\) |
| 3. | \(12.56 \times 10^{-2}~\text{T}\) | 4. | \(12.56 \times 10^{-4} ~\text{T}\) |