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).

[Force Sensitive Resistor]

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 12.0 k and the FSR has a resistance of 70.0 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 FSR when there is no force being applied to the FSR?

Tries 0/10

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

Tries 0/10

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?

Tries 0/10

Suppose that if a force of 1.40 N is applied to the FSR, its resistance decreases to 4.00 k. What would be the new current through the fixed resistor, R?

Tries 0/10

What would be the electric potential at Location A between the two resistors with the applied force of 1.40 N?

Explanation / Answer

a )

I = 5 / ( 12 + 70 ) X 103  

= 6.097 X 10-5 A

b )

the both FSR and fixed resistros are in series

so the current will be same

then

I = 5 / ( 12 + 70 ) X 103  

= 6.097 X 10-5 A

c )

the voltage = 6.097 X 10-5 X 12000

= 0.73164 volts

d )

I = 5 / ( 12000 + 66000 )

I = 6.41 X 10-5 A

e )

V = 6.41 X 10-5 X 12000

V = 0.7692 volts

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