There are a variety of sensors which work on the basis of changing resistance du

Question

There are a variety of sensors which work on the basis of changing resistance due to an external influence. For example, force-sensitive resistors (FSR) will change their resistance when a force is a exerted (when you squeeze them).

Computers are good at reading out voltages, so these devices are often combined ith a fixed-value resistor to create a voltage divider circuit. Consider the circuit shown below where the fixed resistor, R, has a resistance of 10.0 k and the FSR has a resistance of 50.0 k when there is no force acting on the FSR. A voltage V=5.00 V is being applied to the two series resistors.

What is the current flowing through the fixed resistor when there is no force being applied to the FSR?

Consider the negative terminal of the voltage source to be at a potential of zero Volts. What is the electric potential (voltage) at the location A between the two resistors?

Suppose that if a force of 1.10 N is applied to the FSR, its resistance decreases to 7.00 k. What would be the new current through the fixed resistor, R?

What would be the electric potential at Location A between the two resistors with the applied force of 1.10 N?

Explanation / Answer

a) Curret through FSR

I= 5/(10k+50k) = 8.3*10-5 Ampere

b) since both FSR and fixed resistor are in series curent will be same

hence current throuh R is also

I= 5/(10k+50k) = 8.3*10-5 Ampere

c) voltage at location A is

V -0 = 8.3*10-5* 10*103 = 0.83 volt

d) I = 5/(10k+7k) = 2.94*10^-4 A

e) potential at A

V-0= 2.94*10^-4* 10*103 = 2.94 volt

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