The image shows that an electromagnet made with a 1.5-volt battery (on the left). how would the strength of an electromagnet be affected if you replaced its 1.5-volt battery with a 9-volt battery (shown on the right) while using the same nail and coil? a. the magnetic field strength would increase. b. the magnetic field strength would decrease. c. the change would not affect the magnetic field. d. the magnetic field would change direction more frequently