Question

which of the following pairs could we test the relationship between to examine circuits that produce magnetic fields?
compass angle and voltage
battery shape and voltage
resistor shape and voltage
wire length and current

Explanation:

To examine circuits producing magnetic fields, we need a pair linking a circuit variable to a measurable magnetic field effect. A compass angle changes in response to magnetic field strength, which is related to circuit voltage (since voltage affects current, which creates magnetic fields). The other pairs do not connect to magnetic field measurement: battery shape doesn't impact voltage/magnetic fields, resistor shape doesn't link to voltage in a way that tests magnetic fields, and wire length vs current doesn't directly measure magnetic field output.

Answer:

compass angle and voltage