A conducting sphere of radius 10 cm is charged to 10 μ C. Another uncharged sphere of radius 20 cm is allowed to touch it for some time. After that if the spheres are separated then surface density of charges, on the spheres will be in the ratio of:
A conducting sphere of radius 10 cm has an unknown charge. If the electric field 20 cm from the centre of the sphere is 1.5 × 103 N/C and points radially inward, what is the net charge on the sphere?