Lecture 4

Question 1

A balanced bridge means:

Answer 1

R1R3=R2R4

Question 2

An active arm is represented by:

Answer 2

Change in R + R

Question 3

With one active arm, temperature and tension

Answer 3

increase

Question 4

Does one active arm compensate for temperature?

Answer 4

No

Question 5

Where should a dummy gauge be placed to negate temperature effects?

Answer 5

Adjacent arm

Question 6

Each of the parameters of inductive sensors can be changed by:

Answer 6

mechanical means

Question 7

LVDT stands for:

Answer 7

linear variable differential transformer

Question 8

LVDT is used to measure

Answer 8

pressure, displacement, and force

Question 9

in LVDTs, ________ changes as core moves

Answer 9

permeability of medium

Question 10

LVDTs require addition of :

Answer 10

phase sensitive demodulation

Question 11

Formula for capacitive sensors

Answer 11

C =Q/V = e0e1A/d

Question 12

As force is applied in capacitive sensors

Answer 12

separation distance goes down, capacitance goes up

Question 13

Piezoelectric sensors do not require an:

Answer 13

energy source

Question 14

Piezoelectric sensors generate an:

Answer 14

electric potential when mechanically strained

Question 15

Applications of piezoelectric sensors

Answer 15

accelerometers, force plates, ultrasound

Question 16

Equation for piezoelectric sensors

Answer 16

q = kf

Question 17

An electromotive force(emf) in volts, exists across the junction of two dissimilar metals

Answer 17

Thermocouples

Question 18

Equation for Thermocouples

Answer 18

E(emf) =F(T1=T2)

Question 19

Advantages of Thermocouples

Answer 19

reduction of non linearity, better sensitivity, greater range of temperatures in the linear region

Question 20

Are semiconductors made of ceramic materials that are thermal resistors with a high negative temperature coefficient

Answer 20

Thermistors

Question 21

In thermistors: As _______ goes up ______ goes down.

Answer 21

temperature; resistance