Consider the circuit shown below. Your power supply has a voltage of 1.9 V. You

Question

Consider the circuit shown below. Your power supply has a voltage of 1.9 V. You want the current in the ammeter A to be 50.9 mA. The resistor R3 is a potentiometer that is a variable resistor that can be changed from 0 to 200 . In addition to the potentiometer you have one of each of the following resistors available of values 22 and 1000 (one of each). Which resistor(s) will have to be used for R1? More than one answer may be correct. Neither the 22 or 1000 resistor will work for 1.9 V. Either the 22 or 1000 resistors will work for 1.9 V. The 1000 resistor will work, but we would need to substantially increase the voltage of the power supply higher than 1.9 V. Only the 22 resistor will work for 1.9 V. Only the 1000 resistor will work for 1.9 V.

Explanation / Answer

lets use R1=22 ohms

then R2=1000 ohms

let R3=R

then voltage across R2=R*0.0509

current through R2=0.0509*R/1000...(1)

now 0.0509*R+22*((0.0509*R/1000)+0.0509)=1.9

solving for R,we get

R=14.998 ohms

so answers are:

R1=22 ohms

R2=1000 ohms

R3=14.998 ohms

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