A set of '\(n\)' equal resistors, of value '\(R\)' each, are connected in series to a battery of emf '\(E\)' and internal resistance '\(R\)'. The current drawn is \(I.\) Now, if '\(n\)' resistors are connected in parallel to the same battery, then the current drawn becomes \(10I.\) The value of '\(n\)' is:
1. | \(10\) | 2. | \(11\) |
3. | \(20\) | 4. | \(9\) |
A potentiometer is an accurate and versatile device to make electrical measurements of E.M.F. because the method involves:
1. | the potential gradients. |
2. | a condition of no current flow through the galvanometer. |
3. | a condition of cells, galvanometer, and resistances. |
4. | the cells. |
The potential difference \(V_\mathrm{A}-V_\mathrm{B}\) between the points \(\mathrm{A}\) and \(\mathrm{B}\) in the given figure is:
1. | \(-3~\text{V}\) | 2. | \(+3~\text{V}\) |
3. | \(+6~\text{V}\) | 4. | \(+9~\text{V}\) |
Two metal wires of identical dimensions are connected in series. If \(\sigma_1\)
1. | \(\frac{2\sigma_1 \sigma_2}{\sigma_1+\sigma_2}\) | 2. | \(\frac{\sigma_1 +\sigma_2}{2\sigma_1\sigma_2}\) |
3. | \(\frac{\sigma_1 +\sigma_2}{\sigma_1\sigma_2}\) | 4. | \(\frac{\sigma_1 \sigma_2}{\sigma_1+\sigma_2}\) |
A potentiometer wire of length \(L\) and a resistance \(r\) are connected in series with a battery of EMF \(E_{0 }\) and resistance \(r_{1}\). An unknown EMF is balanced at a length l of the potentiometer wire. The EMF \(E\) will be given by:
1. \(\frac{L E_{0} r}{l r_{1}}\)
2. \(\frac{E_{0} r}{\left(\right. r + r_{1} \left.\right)} \cdot \frac{l}{L}\)
3. \(\frac{E_{0} l}{L}\)
4. \(\frac{L E_{0} r}{\left(\right. r + r_{1} \left.\right) l}\)
\(\mathrm{A, B}~\text{and}~\mathrm{C}\) are voltmeters of resistance \(R\), \(1.5R\) and \(3R\) respectively as shown in the figure above. When some potential difference is applied between \(\mathrm{X}\) and \(\mathrm{Y}\), the voltmeter readings are \({V}_\mathrm{A}\), \({V}_\mathrm{B}\) and \({V}_\mathrm{C}\) respectively. Then:
1. | \({V}_\mathrm{A} ={V}_\mathrm{B}={V}_\mathrm{C}\) | 2. | \({V}_\mathrm{A} \neq{V}_\text{B}={V}_\mathrm{C}\) |
3. | \({V}_\mathrm{A} ={V}_\mathrm{B}\neq{V}_\mathrm{C}\) | 4. | \({V}_\mathrm{A} \ne{V}_\mathrm{B}\ne{V}_\mathrm{C}\) |
1. | current density | 2. | current |
3. | drift velocity | 4. | electric field |
Two cities are \(150~\text{km}\) apart. Electric power is sent from one city to another city through copper wires. The fall of potential per km is \(8\) volts and the average resistance per km is \(0.5~\text{ohm}\). The power loss in the wire is:
1. \(19.2~\text{W}\)
2. \(19.2~\text{kW}\)
3. \(19.2~\text{J}\)
4. \(12.2~\text{kW}\)