Q. No.In an electrical circuit, a battery is connected to pass \(20\) C of charge through it in a certain given time. The potential difference between two plates of the battery is maintained at \(15\) V. The work done by the battery is:
1. \(100\) J
2. \(200\) J
3. \(300\) J
4. \(400\) J
1. \(90 ~cm\)
2. \(70 ~cm\)
3. \(60 ~cm\)
4. \(50 ~cm\)
| 1. | \(20~\text V\) | 2. | \(30~\text V\) |
| 3. | \(40~\text V\) | 4. | \(75~\text V\) |
A conducting sphere of the radius \(R\) is given a charge \(Q.\) The electric potential and the electric field at the centre of the sphere respectively are:
| 1. | zero and \(\frac{Q}{4 \pi \varepsilon_0 {R}^2}\) | 2. | \(\frac{Q}{4 \pi \varepsilon_0 R}\) and zero |
| 3. | \(\frac{Q}{4 \pi \varepsilon_0 R}\) and \(\frac{Q}{4 \pi \varepsilon_0{R}^2}\) | 4. | both are zero |
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Two tiny spheres carrying charges \(1.8~\mu\text C\) and \(2.8~\mu\text C\) are located at \(40~\text{cm}\) apart. The potential at the mid-point of the line joining the two charges is:
1. \(3.8 × 10^4~\text V\)
2. \(2.1 × 10^5~\text V\)
3. \(4.3 × 10^4~\text V\)
4. \(3.6 × 10^5~\text V\)
| Assertion (A): | The lightning conductor at the top of high building has sharp pointed ends. |
| Reason (R): | The surface density of charge at sharp points is very high resulting in setting up of electric wind. |
In the light of the above statements choose the correct answer from the options given below:
| 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. | Both (A) and (R) are false. |
Work done when a point charge \(0.2~\text{C}\) is moved from infinity to a given point P is \(20~\text{J}.\) The potential at point P is: (potential at infinity is zero)
1. \(20~\text{V}\)
2. \(100~\text{V}\)
3. \(200~\text{V}\)
4. \(\text{Zero}\)
What is the potential difference between \(A\) and \(B\)?
1. \(0\) volts
2. \(10^6\) volts
3. \(2\times 10^6\) volts
4. \(7.5\times 10^6\) volts
| 1. | a scalar quantity |
| 2. | a vector quantity |
| 3. | sometimes scalar but sometimes it is a vector quantity |
| 4. | a tensor quantity |
| 1. | Body of metal is equipotential. |
| 2. | Field lines are perpendicular to the metal surface. |
| 3. | Electrostatic potential inside a metal body is zero. |
| 4. | Electrostatic field inside metal is zero. |
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