PHYS345 Electricity and Electronics

Special Problem 2.2

An inquisitive child finds an additional D-cell and exuberantly sets out to increase the brightness of the flashlight by hooking the third battery directly across the lamp as shown. Much to the child's chagrin, the lamp shines less brightly than in Special Problem 2.1.

Please analyze the circuit using the directions for the left and right branch currents specified in the figure.

a.  Apply the junction theorem at point A to find the current i3 through the lamp.

b.  Apply the loop theorem on the left inner loop, clockwise from point A.

c.  Apply the loop theorem on the right inner loop, counterclockwise from point A.

d.  Solve for the currents i1, i2, and i3.

e.  What is the power now dissipated by the lamp?

f.  What is the terminal voltage of the third D-cell added?

[flashlight circuit]

Last updated Sept. 8, 1998.
Copyright George Watson, Univ. of Delaware, 1998.