Chapter 2 - Sensing

Question 1

Current (I) =

Answer 1

Q/t , rate of flow of charge

Question 2

Voltage (V)=

Answer 2

J/Q Energy per coulomb IR

Question 3

Kirchhoffs 1st law- (Current being split.)

Answer 3

Sum of all currents into a junction = sum of all current out. gets split based on each paths resistance. (more R= less I)

Question 4

State Ohms law

Answer 4

Provided you dont change the temperature and use a passive conductor(not a source of V) V∝I which gives us V=IR

Question 5

Conductance (G) =

Answer 5

I/V measured in Siemens (S)

Question 6

Graph for V and I with a diode, resistor and a lightbulb?

Answer 6

Question 7

Resistance and conductance total for series?

Answer 7

R_total=R₁+R₂ or 1/G_T=1/G₁+1/G₂

Question 8

Resistance and conductance total for parellel?

Answer 8

_{<span>G</span>total}=G₁+G₂ or 1/R_T=1/R₁+1/R₂

If its 2 in parellel - R_T=Product/Sum

For any number of equal resistors in parellel

n x G or 1/n x R

Question 9

2 properties of a real power source

Answer 9

1. has Emf
2. internal resistance

Question 10

Emf (ε)=

Answer 10

terminal voltage + lost voltage

V +Ir (r=internal resistance)

Question 11

define potential divider

Answer 11

a series of resistors or capacitors which can be tapped at any intermediate point to produce a specific fraction of the voltage applied between its ends.

Question 12

Potential divider equation=

Answer 12

Vo/V_i=R_b/R_Total

_{or % of total resistance = % of total voltage}

_{if its wire instead}

V_o/V_i=L_b/L_Total

Question 13

Random uncertainties-

Answer 13

lack of precision

quantify it as +- 1/2 smallest reading

reduced by repeats

instruments can lead to random fluctuations

Question 14

Systematic error-

Answer 14

lack of accuracy

not removed by averaging

can use graphs to remove

Question 15

Response time-

Answer 15

time it takes the equipment to read the thing youre changing

Question 16

Systematic drift-

Answer 16

reading dosnt stop it continues past the value, eq the wire continually stretched when a force was applied (in YM expt)

Question 17

Resolution-

Answer 17

smallest change you can make to the input that will be picked up by the equipment (output)

Question 18

Sensitity=

Answer 18

ΔOutput/ΔInput

units depend on what youre measuring

Question 19

Input resolution=

Answer 19

output resolution/sensitivity

(Δy_min=sensitivity*x_min)