Earth's Magnetism

Q. 46. A uniform disc of mass M and radius R issuspended in vertical plane from a point on itsperiphery. Its time period of oscillation is

Q. Find the dimensions of mass if density , frequency , velocity are chosen as fundamental units

Q. If atmospheric electric field is approximately $150\text{V/m}$ and radius of the earth is $6400\text{km}$, then total charge on the earth's surface is

1. $6.8\times {10}^4\text{C}$
2. $6.8\times {10}^9\text{C}$
3. $6.8\times {10}^6\text{C}$
4. $6.8\times {10}^5\text{C}$

Q. Earth's magnetic field always has a horizontal component except at or Horizontal component of earth's magnetic field remains zero at

1. Equator
2. Magnetic poles
3. A latitude of ${60}^{\circ }$
4. An altitude of ${60}^{\circ }$