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Lamp Circuits

 

1.      Connect one lamp and the battery pack so the lamp will glow.  How bright is it? 

 

 

 

 

2.      Try the other lamp.  Does it glow as brightly as the other does?  What can you say about their resistances?

 

 

 

 

3.      The maximum specifications for the #222 light bulbs used in this exercise are:  2.25V, 0.25A.   What are the resistances of each lamp?  What is the maximum power each can dissipate before each burns out?  According to your answer, what should happen if you connect one light bulb across the battery pack?

 

 

 

 

 

 

 

4.      Connect the two lamps in series.  Draw the circuit.  What do you observe?  Explain what you observe.

 

 

 

 

 

 

 

 

5.      Connect the two lamps in parallel.  Draw the circuit.  What do you observe? Explain what you observe.

6.      In the box you will find two resistors, one with a clear plastic covering and the other which is black.  Describe a way to tell the resistance of each relative to a lamp (bigger or smaller than a lamp).  Draw the necessary circuit(s).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

7.      What is the relative resistance of the one with the clear plastic cover?

 

 

 

 

8.      What is the relative resistance of the one with the black cover?

 

 

 

  

9.  Make a light dimmer out of the variable resistor (“pot”), lamp and battery.  Draw the circuit.

 

 

 

 

 

10. We will now use the red ammeter in the box to calculate the resistance of the resistor with black and brown bands painted on it.   One of the connections should be made to the black connector on the meter.  The other connection to one of the red ones.  The number above the red connector tells you the maximum current in milliamps that the meter can accurately read.  Connect the battery, ammeter and resistor in series. If the meter needle goes off scale to the left, switch the leads.  If the meter needle goes off scale to the right, go to a higher maximum current connector.  Measure the current.  Using the measured current, the voltage of the battery pack and Ohm's law, calculate the resistance, in Ohms, of the banded resistor.