Cracking the SAT Physics Subject Test

4. In which direction will current flow and why?


5. What’s the overall emf?


6. What’s the current in the circuit?


7. At what rate is energy consumed by, and provided to, this
   circuit?

Here’s How to Crack It

4. The battery whose emf is ε 1 wants to send current clockwise, while the
   battery whose emf is ε 2 wants to send current counterclockwise. Since ε 2 > ε 1 ,
   the battery whose emf is ε 2 is the more powerful battery, so the current will
   flow counterclockwise.