You can increase the strength of an electromagnet’s field by
a.
decreasing the current in the solenoid.
b.
decreasing the number of loops in the solenoid.
c.
using a stronger ferromagnetic material for the core.
d.
winding the coils more loosely.

(2) (a) you have a simple circuit that consists of only a battery (δvbat=1.5v) and two resistors with resistance r1=10ω and r2=5ω, connected in series with each other. what is the current running through the battery? (b) you re-arrange your circuit so now r2 is attached in parallel to r1 rather than in series. what is the current running through the battery? (c) you add an additional resistor r3=7ω on the same branch as r2. what is the current running through the battery? (d) what is the power dissipated in r3?