When the planet Jupiter is at a distance of 824.7 million kilometers from the Earth, its angular diameter is measured to be 35.72” of arc. Calculate the diameter of Jupiter.

The earth- moon distance is about 60 earth radius. Moon is seen to be of (1//2)^@ diameter from the earth. From parallax measurement, the sun is found to be at a distance of about 400 times the earth-moon distance. Estimate the ratio of sun earth diameters.

The moon is observed from two points P and Q on the earth which are diametrically opposite. The angle subtended at moon by two directions of observation is 1@(54)' . The diameter of earth is 1.27xx10^(7)m . Calcualte the distance of moon from the earth.

When observed from the earth,the angular diameter of the solar disc is 32 minutes of arc .Determne the diameter of the image of the sun formed by a convex lens of focal length 25 cm.

A circular coil of radius 8.0 cm and 20 turns is rotated about its vertical diameter with an angular speed of 50 rad s^-1 in a uniform horizontal magnetic field of magnitude 3.0xx10^-2 . Obtain themaximum and average emf induced in the coil. If the coil forms a closed loop of resistance 10 Omega , calculate the maximum value of current in the coil. Calculate the average power loss due to Joule heating. Where does this power come from?

Mars has approximately half of the earth's diameter. When it is closest to the earth it is at abot 1/2 A.U. from the earth. Calculate what size it will appear when seen through the same telescope.

A pole has to be erected at a point on the boundary of a circular park of diameter 13 metres in such a way that the differences of its distances from two diametrically opposite fixed gates A and B on the boundary is 7 metres. Is it possible to do so ? If yes, at what distances from the two gates should the pole be erected ?

A circle is the locus of a point in a plane such that its distance from a fixed point in the plane is constant. Anologously, a sphere is the locus of a point in space such that its distance from a fixed point in space in constant. The fixed point is called the centre and the constant distance is called the radius of the circle/sphere. In anology with the equation of the circle |z-c|=a , the equation of a sphere of radius is |r-c|=a , where c is the position vector of the centre and r is the position vector of any point on the surface of the sphere. In Cartesian system, the equation of the sphere, with centre at (-g, -f, -h) is x^2+y^2+z^2+2gx+2fy+2hz+c=0 and its radius is sqrt(f^2+g^2+h^2-c) . Q. Radius of the sphere, with (2, -3, 4) and (-5, 6, -7) as xtremities of a diameter, is

Observe the following facts : (1) The distance from the Earth to the Sun is 149,600,000,000m (2)The speed of light is 300,000,000 m/sec. (3) Thickness of class VII Mathematics book is 20mm (4) The average diameter of a Red Blood cell is 0.00007mm. (5) The thickness of human hair is in the range of 0.005 cm to 0.01 cm. (6) The distance of moon from the Earth is 384,467,000 m. (approx.) (7) The size of a plant cell is 0.00001275m. (8) Average radius of the Sun is 695000km. (9) Mass of propellant in a space shuttle solid rocket booster is 503600kg (10) Thickness of a piece or paper is 0.0016cm. (11) Diameter of a wire on a computer chip is 0.000003m. (12) The height of Mount Everest is 8848m. There some large number like 150,000,000,000m and some every small numbers like 0.000007m. Identify very large and very small numbers from the above facts and write them in the adjacent table.

Calculate the magnetic field due to a circular coil of 250 turns and of diameter 0.1m, carrying a current of 7A at a point on the axis of the coil at a distance 0.12m from the center of the coil.