Physics Help Forum new potential ques(wit attachment)

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Feb 19th 2009, 04:34 AM   #1
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new potential ques(wit attachment)

A gasoline gauge for an automobile is shown schematically in the following illustration. The indicator (on the dashboard) has a resistance of 10 Ω. The tank unit is simply a floar connected to a resistor that has resistance of 140 Ω when the tank is empty, 20 Ω when full, and varies linearly with the volume of gasoline. Find the current in the circuit when the tank is
a. empty
b. half full
c. full
Attached Images
 quescirc.bmp (949.3 KB, 1 views)

 Feb 20th 2009, 07:59 PM #2 Senior Member   Join Date: Apr 2008 Location: HK Posts: 886 I guess the chassis is a conductor which completes the circuit V=IR a) 12=I (140+10) I=0.08A b)let resistance be R 20=140-kV, where k is a proportional constanat and V is the volume k=120/V V1=V/2 R=140-(120/V)(V/2) R=80 12=I(10+80) I=0.133A c) 12=I (20+10) I=12/30 I=0.4A

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