In the adjoining figure a cyindrical wrapper of flat tablets is shown. The radius a tablet is 7 mm and its thickness is 5 mm. How many such tablets are wrapped in the wrapper?

A coil of radius 200 mm is to produce a field of 0.4 G in its centre with a current of 0.25 A. How many turns must be there in the coil ?

A point object ‘O’ is placed on the axis of a cylindrical piece of glass of refractive index 1.6 as shown in the figure. One surface of the glass piece is convex with radius of curvature 3 mm. The point appeared to be at 5 mm on the axis when viewed along the axis and from right side of convex surface. The distance of the point object from the convex surface is

The temperature of the filaments of a 100W electric lamp is 2727^@C . The emissivity of the surface of the filament is 0.086 and its radius is 0.5 mm. Find the length of the filament. sigma = 5.7 xx 10^-8 S.I. units.

₹ 5 coins were made by melting a soild cuboidal block of metal with dimensions 16 times 11 times 10 in cm. How many coins of thickness 2 mm and diameter 2 cm can be made. (pi=22/7)

Choose correct alternative. An electric cable contains a single copper wire of radius 9 mm. Its resistance is 5 Omega . This cable is replaced by six insulated copper wires, each of radius 3 mm. The resultant resistance of cable will be A. 7.5 Omega B. 45 Omega C. 90 Omega D. 270 Omega