physical quantities and units Flashcards
What are Physical Quantities?
It is a quantity that has a magnitude and a unit
What are Base Quantities?
Those quantities which require only one measurment
What are Base Units?
The units of the base quantities
What are the units of the 7 fundamental base quantities?
Time= Seconds Mass= Kg electric current= Ampere Luminosity= Candela amount of substance= Mol Temperature= Kelvin Length= Meter
What are derived quantites?
They are usually the products and quotients of base quantities.
What is a homogeous equation?
An equation is set to be homogenous if the base units of every term in the equation is identical
what are the answers to the prefixes?
kilo mega giga tera peta Esa milli micro nano pico femlo alto ?
chart on notes
What is compound errors?
Errors in the measurement of the various physical quantities are compounded in the resulted quantity results in large error. This is called compound errors
what are systematic errors?
these are uncertainties in the in the measurement of the physical quantity due to fault of instruments, The characteristic of the error is that the size of the error is roughly constant and the reading may be greater or less than the actual value and repeating the experiment or taking average wont fix it only using better equipment and better experimental techniques will.
How to reduce systematic error?
1) Change Instrument
2) Check for zero error
3) Take the reading of a known value
4) Change the observer and let him use his own equipment
What are Random Errors?
they are uncertainties or mistakes in a measurement made by the observer taking the measurement. The characteristic of the random error is that it can be greater or less than the actual value and the magnitude of the error is not constant. It can be reduced by repeating the experiment and taking average.
what are the sources of random error?
1) parallex error, when your line of sight isnt perpendicular to the reading while measuring
2) sudden wind and temperature changes may affect the experiment
3) applying different pressures while closing vernier caliper and micrometer screw gauge
What is precision?
It is the average deviation of a reading from the the mean reading .
What is accuracy?
A measurement is said to be accurate if it is close to the actual value.
The accuracy of the measured by calculating the percentage error. The smaller the percentage error the greater the accuracy
what is one mm in cm?
1mm=0.1cm
What is range and least count of meter rule?
Range: 100cm/1m
Least count: 1mm/0.1cm
what is range and least count of vernier caliper?
Range:2-10cm or 10-20mm
least count: 0.1mm/0.01cm
What is the range and least count of micrometer screw gauge?
Range: Less than 2 cm
Least Count: 0.01mm or 0.001cm
How to measure with vernier Caliper?
1) open outside jaw and close it according to object
2) take mainscale reading
3) take vernier scale reading x least count
4) add both readings
how to check zero error on vernier caliper?
the jaws should be closed and both zeroes should coincide
how to take volume of irregular object?
1) take measuring cylinder
2) fill it with water and take reading R1
3) use thread to attatch object with and lowe it in water and take reading R2
4) R2-R1 = volume of object
How to measure volume of object by displacement can?
1) Fill the displacement can up to the level marked
2) place the object inside
3) liquid accumulated in MS is volume
what is the apparatus used to measure mass?
1) electronic balance
2) beam balance
What is the apparatus to measure weight?
Newton meter.
What is the apparatus to measure time?
digital stopwatch (0.1s) mechanical stopwatch(0.01s)
What is used to measure current? and how is it connected in a circuit?
Ammeter connected in series
what is used to measure voltage in a circuit and how is it connected?
Voltmeter and connected in parallel
what are the sources of systematic error?
zero error
change in environment
equipment calibration problem
