To apply the biot-savart law to find the magnetic field produced on the z axis from current elements in the xy plane. in this problem you are to find the magnetic field component along the z axis that results from various current elements in the xy plane (i. e., at z=0).

when a device is used in a circuit in which the voltage is 81 v, the current flowing through the device is 3 a. what is the resistance of the device?

a. 27 ω

b. 40.5 a

c. 243 ω

d. 243 a

the correct answer is a. 27

what experimental evidence led scientists to change from the previous model to this one?

a few of the positive particles aimed at a gold foil seemed to bounce back.

the colors of light emitted from heated atoms had very specific energies.

experiments with water vapor showed that elements combine in specific proportions.

cathode rays were bent in the same way whenever a magnet was brought near them.

i think the answer is a, hope this : )