Deck 2: Sensing 1 Flashcards
What is ion beam machining?
Were argon ions are made by firing electrons at argon atoms. The ions are then accelerated into a beam and the ions knock atoms out of the material, making materials such as diamond sharper.
Why must a beam of ions travel in a vacuum?
- A beam of ions carries a current
- If not the ions collide into gas molecules and scatter.
What creates potential diffirence?
Uneven distributions of charge.
Explain how a dry cell produces a potential diffirence?
The chemical reaction drives electrons to one pole leaving positive charge at the other. The diffirence in distribution of charges creates a potential diffirnce between poles.
Q= I= V= E= P= t=
Q= Charge in coulombs(c) I= current in amperes(A) V= potential diffirence in volts (V) E=Energy in joules(J) P= Power in watts(W) T=time in seconds(s)
What is electric current and what equation is used to calculate it?
1) Electric current is the rate of flow of charge
2) I = Q / t -> I=Current(A), Q=charge(c), T=time(s)
What is electrical potential diffirence and what equation is used to calculate it?
1) Electrical potential diffirence V between two places is the diffirence in potential energy E of a charge Q going between those two places.
2) V= E / Q -> E=energy(j), Q=charge(c)
What is power and how is it calculated?
Power P is the rate of electricity of energy E. P=E/t
What is conductance?
Conductance is the current for a given potential diffirence.
- G=I/V
- G=1/Resistance
What is resistance?
Resistance is the potential diffirence needed for a given current .
- R=V/I
- Resistance = 1/conductance
What is the relationship between conductance and resistance?
They are the inverse of each other.
What is ohms law?
Provided the temperature is constant, the current through an ohmic conductor is directly proportional to the potential diffirence across it.
Give a reason to produce microchips small?
One reason to build microchips small is to reduce delay times.
In parallel circuits what adds up?
1) Conductances add up (Gt=G1 + G2)
2) Currents add up
3) Potential diffirence remains constant
In series circuits what adds up?
1) Resistances add up ( Rt=R1 + R2)
2) Current is constant
3) Potential difference adds up.
What is the unit for conductance?
1) Amperes per volt
2) Siemens(S)
What are potential dividers used for ( generally ) ?
Potential dividers are used to control the potential diffirence coming out of resistors.
How do potential dividers work?
A potential divider taps off a fraction of its input, to provide a controlled output.
Why do the potential dividers in fuel gauges not give a linear graph for amount of fuel left vs voltage output?
Many fuel gauges do not move round the dial by equal amounts for equal numbers of litres of petrol used up, the sacle is non-linear. This is because the petrol tanks have an odd shape to fit in the space available.
What is a calibration curve?
A calibration curve is used to tell you how to look up the input to a measuremen system if you known its output. Calibration curves are often built into sensor systems as look up tables relating input to output..
How can electromotive force be calculated?
- E= Vexternal + Vinternal
- E= IRexternal + IR internal
