Physical Quantities & Measurement Flashcards
(45 cards)
what is the SI unit of energy?
The SI unit of energy is Joule (J).
What is Physics?
Physics is the study of matter and energy and the mutual relation between them.
What are physical quantities?
The quantities which can be measured are called physical quantities & consists of a magnitude and unit.
Name the physical quantities.
mass (kg)
Time (s)
length (m)
temp. (K)
current (A)
intensity of light (cd)
amount of substance (mol)
what are base quantities?
base quantities form the base or foundation of other physical quantities. All other physical quantities are derived from them.
what are derived physical quantities?
derived quantities are expressed in terms of base quantities.
what is a numerical magnitude?
Numerical magnitude is the number representing the size of the quantity
what is a unit?
A unit is a standard with which physical quantities are compared.
what are base units?
in si seven physical quantities are chosen as base and their units are defined and standardized. theses units are called base units. Each SI unit is defined carefully so that accurate and reproducible measurements can be made.
what are derived units?
The units used to measure derived quantities are called derived units. units of derived quantities are obtained by multiplying or dividing base units. Derived units are expressed in terms of base units.
what is scientific notation?
SN is an easy method of writing very small or very large numbers in the power of ten. In SN a no. is expressed in some power to ten multiplied by a number between 1 and 10
what is mantissa?
part of a number located after a decimal point.
what are prefixes?
Si units have the advantage that their multiples and sub-multiples can be expressed in terms of prefixes. A mechanism through which numbers expressed in the power of ten are given a proper name is called prefixes. Prefixes are useful for expressing units of physical quantities that are either very large or very small.
What are measuring instruments?
Measuring instruments are used to measure various physical quantities such as length, mass time etc
What is a metre rule?
A meter rule is a length-measuring instrument that is one meter long. It is used to measure the length of objects or the distance between two points. It is equal to 100 cm. Each cm is divided into 10 mm. Thus, 1 mm is the smallest reading that can be taken using a meter rule and is called its least count.
what is a measuring tape?
Measuring tapes are used to measure the length in meters and cm. A measuring tape consists of a thin and long strip of cotton, metal, or plastic generally 10m, 20m, 50m, or 100m long. Measuring tapes are marked in cm as well as in inches.
prefixes in order with a power of ten.
what is a vernier caliper?
a measuring device that is used for the measurement of linear dimensions. A Vernier caliper can help take a reading smaller than a millimeter. It can measure the thickness, diameter, or width of an object and the internal and external diameter of a hollow cylinder.
A Vernier caliper consists of two jaws. One is a fixed jaw with a main scale attached to it. The main scale has centimeter and millimeter marks on it. The other is a movable jaw. There are two scales on Vernier Caliper. The main scale has markings of usually 1 mm each and it contains a jaw on its left end.
A sliding scale called the vernier scale is marked with divisions slightly smaller than the division of the main scale.
For example, a vernier scale could have 11 markings for each 10 on the main scale. That’s 10 divisions on the vernier scale for every 9 on the main scale.
What is zero error and zero correction?
On closing the jaws of the Vernier Caliper, the zero of the vernier scale should coincide with the zero of the main scale. if their zeros do not coincide, there is an error in the instrument called a zero error.
steps for taking reading on a scale
when is the zero error positive
when zero line of VS is on the right side of the zero of the MS
what is the zero error called when the zero of the VS is on the left side of the zero of the MS?
Negative zero error
when do we have to add or subtract measurement with zero error?
if +ve zero error subtract it from the measurement
if -ve zero error, add it with the measurement.
what does the accuracy of measuring significant figures depend on?
the quality of the measuring instrument.
the skill of the observer
the number of observations made
