This problem requires two dissimilar light bulbs.  Example light bulbs are shown in the photo below.  If you look at the light bulbs closely they are not the same.  Here's what you should note.

• The two light bulbs are designed to operate from the same voltage source.  Call the value of that source V_s.
• When operated from the same source voltage, the two light bulbs dissipate different amounts of power.  Call the power values P₁ and P₂.
• As questions are raised in this lesson, you should record your answers and any supporting experimental observations in your laboratory notebook.  You will need that data and those thoughts to write your report.  Questions that you should answer will always be colored dark blue.

• Your analytical/paper work should be done and handed to your instructor before you begin the experimental work.
• Your analytical work should be done entirely symbolically.  You will not learn values for the bulbs until you have done the theoretical work.
• The first thing you should do is to answer the following questions.
• If the two light bulbs are wired in parallel, which light bulb will give off the most light?
• Since the two light bulbs dissipate different amounts of power when connected to the same voltage, which light bulb will give off the most light?
• Devise an experimental scheme to determine which light bulb has the higher power/wattage rating.
• Now, consider what happens when the light bulbs are wired in series.
• Predict which light bulb will give off the most light when the supply voltage is applied to the series combination.  Is it the higher power or the lower power bulb?
• Enter your argument into your lab book.  It should be written as a convincing argument - i.e. one which would convince someone who knows about power, series resistors, Ohm's Law, etc.
• Hand in your report.
• Now, wire the two light bulbs in parallel.
• Apply the source voltage.
• Determine experimentally which light bulb has the higher power rating. Your instructor will give you the value of the supply voltage you should use.
• Determine experimentally which light bulb gives off the most light.
• Now, connect the bulbs in series.
• Apply the source voltage.
• Determine which bulb gives off the most light.