Physics - Chapter 1 :Physical Quantities, Units and Measurement

State the power factor for : tera giga mega kilo deci centi milli micro nano

tera - 12 giga - 9 mega - 6 kilo - 3 deci - -1 centi - -2 milli - -3 micro - -6 nano - -9

What is a Base quantity? Give examples of base quantities.

A base quantity is a physical quantity that can be directly measured. Examples : length, mass, time, electric current, temperature, amount of substance.

What is a Derived quantity?

A derived quantity is a physical quantity that is derived from base quantities. Examples : Weight, area, speed, volume.

Define physical quantities.

A physical quantity is a quantity that can be measured.

State the SI units for : Length Mass Time Electric Current Temperature Amount of substance

Length - metre (m) Mass - kilogram (kg) Time - seconds (s) Electric Current - ampere (A) Temperature - kelvin (K) Amount of substance - mole (mol)

What is parallax error and how to minimize it?

Parallax error occurs due to wrong positioning of the eye when reading a measurement. It can be minimised by placing the eye vertically above the mark on the scale, when reading the scale of a ruler.

Define precision.

Precision is the smallest unit an instrument can measure.

What is random error and how to minimise it?

Random error is statistical fluctuations in measured data caused by the experimenter's inability to take the same measurement in exactly the same way to obtain the same number. It can be minimised by taking more data, and can be reduced through averaging over a large number of observations.

Define range.

Range is known as the values between minimum value and maximum value that can be measured.

What is systematic error?

Systematic error are repeated inaccuracies that are consistently in the same direction, caused by a problem that persists throughout the experiment.

What is a period?

The period of a pendulum is the time taken for the pendulum to complete 1 oscillation.

What is the precision of digital calipers and micrometer screw gauge?

The precision of digital calipers is 0.001 cm/0.01mm. The precision of a micrometer is 0.0001 cm/ 0.001mm.

What affects period?

When length of a pendulum decreases, the period decreases.

What is zero error and how to remove it?

Zero error is a condition when a measuring instrument registers a reading where there should not be any reading. It can be removed by measuring from another point and subtracting it from the final mark, or pressing the tare function on a measuring instrument before using it.