Uncertaintiy And Measuring Mistakes, Accuracy Flashcards

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1
Q

If they mention measuring something that gives a BIGGER VALUE and whynthat leads to more accuracy what to say?

A

Bigfer value hints at uncertiwnties

It’s likely that you’re using the same uncertainty but bevause you have a bigger number to mewsude over, then the percentage uncertainty decreases and it becomes more accurtse

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2
Q

When you have two pieces of equipment same that are used backed ti back (like meter rulers) what do you to find total uncertainty

A

Add the separate uncertainties together

So meter fuller = 1 mm + 1mm = 2mm

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3
Q

When there is an uncertainty in one thing and they say what percentage ERROR DOES THIS CAUSE IN ANSWER, what does it mean?

So why do we divide by 2 if sqaure root?

A

It just means PERCENTAGE UNCERTAINTY OVERALL

So remember how you add them up, if it’d squared muktilky by two
If it’s sqaure root, divide by 2!!

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4
Q

How to increase accuracy of oscilloscope measure amplitude
1) decreasing uncertainty
2) using means

IMPORTANT

A

1) turn time base off
2) turn y gain down so that the wave stretches higher to its maximum height ( same voltage , less gain so more squares).
- higher height means lower percentage uncertainty overall !
- count the squares peak to peaks , multiply by y gain, divide by 2!

2) 2nd idea is to increase / decrease time gain ti give different heights
- count squares peak to peak multiply by y gain , divide by 2
- do this for many different y gains and heights, count them together AND FIND AVERAGE FOR ACCURATE ANSWER

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5
Q

What does accuracy vs precision mean?

A

Accuracy means how close to is to the actual value

Precision refers to uncertainty!

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6
Q

How to find uncertainty in something like sin theta?

A

The uncertainty in sin theta is just = to the uncertainty in theta
- remember that any function does not CHANGE THE UNCERTAINTY OF A VALUE
- now you may have calculated sin theta but when dealing with theta always use lengths that have been DIRECTLY MEASURED
- therefore typically use tan function rather than calculating hypotenuse for sin
- know that theta = act tan (O/H) and thus uncertainty in theta uncertainty in O/H
Add these up, done !

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7
Q

Remember uncertainties in any measurement is the same as the uncertainty

A

Say you measured 10 wavelengths, uncertainty in one is the same as 10 so it’d less, don’t forget

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8
Q

Random vs systematic error

How to reduce random error

A

Random error is due to things can’t control, to reduce , take repeats
- more precise instruments
- use computers to avoid human error

This suggests that uncertainty in equipment is to do with random errors

2) systematic error is an error that will always be there as a result in a flaw in method or faulty equipment
- this error can easily be fixed, whereas random can’t

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9
Q

Uncertisnty in equipment, what kind of error is that

A

Random, can’t get close to the true value so don’t know what it is, taking it over repeats will probably be better

Might be confusing, just remember

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10
Q

Remember if they don’t give uncertainty like they did in that 6 marker, how can you estimate it ? Anyways so that you can back up your 6 marker

A

Can estimate it by taking the LAST value of the decimal as absolute uncertainty, give so,e number man

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