Grade 6 Physics Chapter 2

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Questions and Answers

What is a physical quantity composed of?

Constant + variable

Numerical value × unit (correct)

Physical dimension × time

Numerical value + constant

Which of the following is a standard characteristic of a unit of measurement?

It can be easily reproduced (correct)

It can change over time

It is extremely large

It is ambiguous and uncertain

Which unit is the SI unit for measuring length?

Centimeter

Millimeter

Kilometer

Meter (correct)

What is the role of standard units in measurement?

To maintain uniformity in measurement Signup and view all the answers

Which of the following is not a rule for writing units?

Symbols are always in upper case Signup and view all the answers

What is the metric equivalent of 1 kilometer?

1000 meters Signup and view all the answers

Which instrument is commonly used to measure small lengths?

Vernier calipers Signup and view all the answers

What is the purpose of defining a 'metre' in relation to a platinum-iridium bar?

To ensure uniformity in measurement Signup and view all the answers

What is the primary device used to measure time accurately?

Atomic clock Signup and view all the answers

Which temperature scale is considered a theoretical scale?

Kelvin Signup and view all the answers

What is the normal body temperature in degrees Celsius?

37 °C Signup and view all the answers

How do you convert Celsius to Fahrenheit using the provided formula?

F - 32 = (C × 100)/180 Signup and view all the answers

What type of thermometer is specifically designed to measure body temperature?

Clinical thermometer Signup and view all the answers

What is the SI unit of temperature?

Kelvin Signup and view all the answers

What happens to mercury in a laboratory thermometer when it is placed in hot water?

It expands and rises up Signup and view all the answers

Which of the following does NOT represent a characteristic of a correct beam balance?

The handle can manipulate the beam Signup and view all the answers

Which option describes approximation in measurement?

Close judgment of measurement Signup and view all the answers

What is the purpose of the Department of Weights and Measures in India?

To maintain correctness of weights and measuring devices Signup and view all the answers

What is the correct method to avoid parallax error when measuring length with a metre scale?

Position your eye directly above the measurement point. Signup and view all the answers

How should you measure the diameter of a spherical object according to the outlined method?

Place wooden blocks beside it and measure the inner distance. Signup and view all the answers

What is the primary purpose of winding a wire around a pencil in the measurement process?

To measure the thickness of the wire accurately. Signup and view all the answers

What is the SI unit of mass?

Kilogram (Kg) Signup and view all the answers

How is the surface area of a regular shape calculated?

By applying a specific formula based on its dimensions. Signup and view all the answers

What distinguishes a beam balance as true?

Its beam remains horizontal with equal weights. Signup and view all the answers

What is the main difference between mass and weight?

Weight changes with location, but mass remains constant. Signup and view all the answers

What precautions should be taken when using an electronic balance?

Check if the digital display reads zero before use. Signup and view all the answers

How is the thickness of a single rupee coin determined using multiple coins?

By measuring the thickness of a stack of coins and dividing by ten. Signup and view all the answers

What is the primary function of a weight box?

To provide standard weights for comparative measurement. Signup and view all the answers

What is the method used to measure the length of a curved line?

By wrapping a thread along the curve and measuring the thread. Signup and view all the answers

What does 1 inch convert to in centimeters?

2.54 cm Signup and view all the answers

What is the standard error that can occur when using a metre scale for measuring?

Parallax error from incorrect eye positioning. Signup and view all the answers

What is the main advantage of using an electronic balance over a traditional balance?

It provides a digital reading for accuracy. Signup and view all the answers

Study Notes

Measurement and Physical Quantities

Measurement compares an unknown quantity with a known constant or unit.
Every measurement consists of a numerical value and a unit.
A physical quantity can be defined as: Physical quantity = Numerical value × unit.
Standard units ensure uniformity and reliability in measurements, avoiding discrepancies due to human body variations.

Need for Standard Units

Prior to standard units, measurements were inconsistent.
Standard units are defined by characteristics that include being of moderate size, unaffected by space and time, unambiguous, non-perishable, and easily reproducible.

Rules for Writing Units

Unit names are written in lower case, except Celsius and Fahrenheit.
Symbols for units named after scientists are in upper case, while other symbols remain in lower case.
Units should not be followed by a full stop and written in plural form only when in words.

Measurement of Length

Length is the distance between two points; the SI unit is the metre (m).
A metre is based on a platinum-iridium bar kept in Paris.
Tools for measuring length include rulers, measuring tapes, vernier calipers, and screw gauges.
Common units include multiples (kilometre, hectometre) and submultiples (decimetre, centimetre, millimetre).
Light-year measures astronomical distances, and microscopic measurements use microns and angstroms.

Measuring Techniques

Accurate measurement requires proper placement and alignment to avoid parallax error.
For spherical objects, measure diameter using solid blocks and a metre scale.
Curved lengths can be measured using a thread, while the thickness of small objects can be determined by stacking.

Measurement of Area

Area represents the surface enclosed by a boundary, measured in square metres (m²).
Regular and irregular areas are assessed differently, with formulas and graph paper used respectively.

Mass and Weight

Mass indicates the amount of matter in an object, while weight represents gravitational force acting on it.
SI unit of mass is kilogram (kg); subunits include gram and milligram.
Balance scales (grocer’s, beam, physical, electronic) are used to measure mass accurately.

Measurement of Time

Time represents the interval between events; the SI unit is the second (s).
Historical methods included sundials; modern timekeeping uses atomic clocks.
Devices include clocks, watches, and stopwatches for various measurements.

Measurement of Temperature

Temperature indicates the degree of hotness or coldness, measured with thermometers.
SI unit is Kelvin; common scales are Celsius and Fahrenheit.
Laboratory thermometers measure up to -100°C to 110°C, while clinical thermometers measure human body temperature.

Approximation in Measurement

Approximation provides a quick but not exact measurement; accuracy reflects closeness to the true value.
Errors can be mitigated by averaging multiple observations.

Standard Weights and Measures

The Department of Weights and Measures in India ensures correctness of weights and measuring devices.
Characteristics of accurate measuring devices include verification stamps and correct functionalities.

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Description

Explore the foundations of measurement in physics with this quiz on physical quantities. Understand how measurement involves comparing unknown quantities with known units and discover the significance of standard units. Test your knowledge on numerical values and units in this essential chapter.