Two lenses are placed along the x axis, with a diverging lens of focal length −9.00 cm on the left and a converging lens of focal length 21.0 cm on the right. when an object is placed 18.0 cm to the left of the diverging lens, what should the separation s of the two lenses be if the final image is to be focused at x = ∞? cm

Currents in dc transmission lines can be 100 a or higher. some people are concerned that the electromagnetic fields from such lines near their homes could pose health dangers. for a line that has current 150 a and a height of 8.0 m above the ground, what magnetic field does the line produce at ground level? express your answer in teslas and as a percentage of the earth’s magnetic field, which is 0.50 g. is this value cause for worry?