Q. No.The amount of positive and negative charges in a cup of water (\(250\) g) are respectively:
| 1. | \(1.6 \times10^9\) C, \(1.4 \times10^9\) C |
| 2. | \(1.4 \times10^9\) C, \(1.6 \times10^9\) C |
| 3. | \(1.34 \times10^7\) C, \(1.34 \times10^7\) C |
| 4. | \(1.6 \times10^8\) C, \(1.6 \times10^7\) C |
If \(10^9\) electrons move out of a body to another body every second, how much time approximately is required to get a total charge of \(1\) C on the other body?
1. \(200\) years
2. \(100\) years
3. \(150\) years
4. \(250\) years
If a body is charged by rubbing it, its weight:
| 1. | remains precisely constant. |
| 2. | increases slightly. |
| 3. | decreases slightly. |
| 4. | may increase slightly or may decrease slightly. |
Given below are four statements:
| (a) | The total charge of the universe is constant. |
| (b) | The total positive charge of the universe is constant. |
| (c) | The total negative charge of the universe is constant. |
| (d) | The total number of charged particles in the universe is constant. |
Choose the correct option:
| 1. | (a) only | 2. | (b), (c) |
| 3. | (c), (d) | 4. | (a), (d) |
1. \(\frac{r}{\sqrt[3]{2}}\)
2. \(\frac{r}{\sqrt[2]{2}}\)
3. \(\frac{2r}{3}\)
4. none of the above
The ratio of the magnitude of electric force to the magnitude of gravitational force for an electron and a proton will be:
(\(m_p=1.67\times10^{-27}~\text{kg}\), \(m_e=9.11\times10^{-31}~\text{kg}\))
1. \(2.4\times10^{39}\)
2. \(2.6\times10^{36}\)
3. \(1.4\times10^{36}\)
4. \(1.6\times10^{39}\)
| 1. | \(\dfrac{-Q}{4}\) | 2. | \(\dfrac{Q}{4}\) |
| 3. | \(\dfrac{-Q}{2}\) | 4. | \(\dfrac{Q}{2}\) |
Consider three charges \(q_1,~q_2,~q_3\) each equal to \(q\) at the vertices of an equilateral triangle of side \(l.\) What is the force on a charge \(Q\) (with the same sign as \(q\)) placed at the centroid of the triangle, as shown in the figure?
| 1. | \(\dfrac{3}{4\pi \epsilon _{0}} \dfrac{Qq}{l^2}\) | 2. | \(\dfrac{9}{4\pi \epsilon _{0}} \dfrac{Qq}{l^2}\) |
| 3. | zero | 4. | \(\dfrac{6}{4\pi \epsilon _{0}} \dfrac{Qq}{l^2}\) |
Consider the charges \(q,~q,\) and \(-q\) placed at the vertices of an equilateral triangle, as shown in the figure. Then the sum of the forces on the three charges is:
1. \(\frac{1}{4\pi \epsilon _{0}}\frac{q^{2}}{l^{2}}\)
2. zero
3. \(\frac{2}{4\pi \epsilon _{0}}\frac{q^{2}}{l^{2}}\)
4. \(\frac{3}{4\pi \epsilon _{0}}\frac{q^{2}}{l^{2}}\)
1. \(v\propto x\)
2. \(v\propto x^{-1/2}\)
3. \(v\propto x^{-1}\)
4. \(v\propto x^{1/2}\)
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