# FRANK Solutions for Class 9 Physics Chapter 1 - Measurement

Revise Frank Solutions for ICSE Class 9 Physics Chapter 1 Measurement at TopperLearning. Go through the three systems of unit. Learn the unit of SI system with textbook solutions by our experts. Also, learn the uses of Vernier calipers in this chapter.

You can achieve top marks in ICSE Class 9 Physics by using our Frank textbook solutions, Selina solutions, etc. for chapter revision. Understand how to measure objects using various measuring instruments while practising the model answers for Chapter 1. Once you understand the chapter concepts, attempting chapter-related questions will become easy for you.

## Chapter 1 - Measurement Exercise 15

(a) C.G.S system - fundamental unit of length is centimetre(cm), of mass is gram(gm), of time is second(s).

(b) F.P.S system- fundamental unit of length is foot(ft), of mass is pound(lb), of time is second(s).

(c) M.K.S system- fundamental unit of length is metre(m), of mass is kilogram(kg), of time is second(s).

(a). Decameter = 10 metre

(b). Hectometer = 100 metre

(c). Kilometer = 1000 metre

(a). Decimeter = 0.1 metre

(b). Centimeter = 0.01 metre

For example, volume= 52.37 m

^{3}then the order of magnitude is 10

^{2}m

^{3}.

^{-6}metre while a millimeter is equal to 10

^{-3}metre.

## Chapter 1 - Measurement Exercise 16

## Chapter 1 - Measurement Exercise 28

Pitch of the screw = distance travelled by screw in n rotations/n rotations

(a). Measuring the internal diameter of a tube or a cylinder.

(b). Measuring the length of an object.

(a). There comes an error of parallax due to thickness of the metre rule.

(b). We cannot use metre rule for measuring small thickness.

Pitch of the screw = distance travelled by screw in n rotations/n rotations

Least count refers to the smallest reading that can be accurately measured while using an instrument. The least count is the value of one division on its scale.

Level of water in cylinder after immersing piece of copper = 50 ml

Volume of copper piece = 50-30 = 20 ml

## Chapter 1 - Measurement Exercise 29

(a). If the zero of the circular scale remains below the line of graduation then it is called positive zero error

(b). If the zero of the circular scale lies above the line of graduation then it is called negative zero error

For positive zero error correction, the zero error should always be subtracted from the observed reading

For negative zero error correction, the zero error must be added to the observed reading.

(a). A linear scale called the main scale graduated in half millimeters

(b). A circular scale divided into 50 or 100 equal parts.

It is avoided by turning the screw always in the same direction.

(a). Calculate the least count and zero error of the screw gauge.

(b). Place the wire in between the studs. Turn the ratchet clockwise so as to hold the wire gently in between the studs. Record the main scale reading.

(c). Now record the division of circular scale that coincides with the base line of main scale. This circular scale division multiplied by least count will give circular scale reading.

(d). The observed diameter is obtained by adding the circular scale reading to the main scale reading. Subtract the zero error if any, with its proper sign, from the observed diameter to get the true diameter.

Circular scale divisions = 100

Least Count of screw gauge = pitch of the gauge/circular scale divisions

= 0.05/100

= 0.0005cm

(a). False, because the accuracy is higher in case of screw gauge due to lower least count value of 0.01mm

(b). True

(c). False, because its least count is limited to 0.1 cm. thus this length can be measured with an instrument of least count of 0.001 cm i.e. screw gauge

(d). False, the ratchet is used to hold the object under measurement gently between the studs.

(e). True

^{3})

^{3}is same as 1 ml.

^{3}= 1000 litre

1 litre = 1/1000 m

^{3}

= 0.001 m

^{3}

## Chapter 1 - Measurement Exercise 30

^{3}(m

^{3}).

The relation between liter and metre3

1 metre

^{3}= 1000 liter

Least count = 0.001 mm

Number of divisions = pitch/least count

= 0.5/0.001

= 500

(a). The sinker should be insoluble in water

(b). The sinker should have a high density than water.

(c). Lower meniscus should be read to note down the readings and error due to parallax should be avoided.

(a). In this case, kerosene or any liquid whose density is lighter than water and in which the solid is not soluble is used.

(b). Fill the graduated cylinder with the liquid.

(c). Record the lower meniscus of liquid and let the value be V

_{1}.

(d). Tie the solid whose volume is to be measured to a strong string and lower it into the water gently.

(e). Note the reading carefully and let the value be V

_{2}

(f). Volume of the solid, V = V

_{2}- V

_{1}

## Chapter 1 - Measurement Exercise 38

^{-2}, is nearly 1 m.

T = 1/f or f = 1/T

^{-2}, is nearly 1 m.

(a). The beam must be gently lowered before adding or removing weights from the pan.

(b). The weights should not be carried with bare hands to avoid the change in weights due to moisture and dust particles from the surrounding.

(c). The lever should be turned gently, in order to prevent knife edges from chipping.

(d). Never keep the wet or hot objects on the pan.

(e). The weights should be placed into weight box after use.

(f). Whenever you are near the actual weight, you should carefully try the weights in the descending order.

(a). Both the pans must be of equal weights.

(b). Both the arms must be of equal lengths.

## Chapter 1 - Measurement Exercise 44

(a). Random errors-these errors are due to various factors. In a number of observations we get different readings every time.

These errors can be minimized by taking observations a large number of times and taking the arithmetic mean of the readings.

(b). Gross error- these errors are due to carelessness of the observer like parallax, improper setting of the instrument.

These errors can be minimized only when the observer is careful in setting up of instrument and taking readings.

(a). Number of significant figures = 3

(b). Number of significant figures = 4

(c). Number of significant figures = 5

Since (c) part has maximum number of significant figures = 5, therefore it is most accurate among the given three.

## Chapter 1 - Measurement Exercise 46

## Chapter 1 - Measurement Exercise 47

^{-15}m while 1 micron is 10

^{-6}m.

No, parsec is not same as astronomical unit (A.U.).

1 Parsec = 2 X 10

^{5}A.U.

^{-2}cm, 10

^{-3}cm depending upon the vernier used. Therefore a vernier caliper is important to measure the fraction of a smallest division of a measuring scale which otherwise could not be done by the judgment of the eye.

^{-2}mm.

(a) If the zero of the scale remains below the line of graduation of the main scale then it is called positive zero error

(b) If the zero of the scale lies above the line of graduation of the main scale then it is called negative zero error

Pitch of the screw = distance traveled by screw in n rotations/n rotations

It is avoided by turning the screw always in the same direction.

^{-6}m.

^{15}m

T = 1/ for f = 1/T

(a). It must be well defined.

(b). It must be of proper size. Very small or large size may cause inconvenience.

(c). It should be easily accessible

(d). It must be reproducible at all places without any difficulty.

(e). It must be accurately defined and must not change with time, place and physical conditions such as pressure, humidity, etc.

(f). It must be widely acceptable all over the world.

## Chapter 1 - Measurement Exercise 48

Least count of screw gauge = 0.01 mm

Thus, zero error = 0 + 4 X L.C. = 0.04 mm

Least count of screw gauge = 0.01 mm

Thus, zero error = (50-47) X L.C.

= 3 X 0.01

= 0.03 mm

Distance covered in 20 threads = 10 mm

Pitch of the screw gauge = 10/20 =0.5 mm

No of divisions on circular scale = 50

Least count = pitch/no of divisions =

= 0.01 mm

(ii) Time period - The time taken by a simple pendulum for an oscillation is known as the time period of a simple pendulum.

(iii) Frequency -the number of oscillation made by the pendulum in one second is called frequency. Its SI unit is Hertz (Hz).

(iv) Amplitude - Amplitude is the magnitude of the maximum deviation of the bob from the mean position on either side when an oscillation takes place.

Volume = 200cm

^{3}

Density = mass of metal/ volume

= 540 /200 = 2.70 g/cm

^{3}

Density of copper = 9 g/cm

^{3}

Volume of copper used in the alloy = mass of copper / density

= 540/9 = 60 cm

^{3}

Mass of iron = 240 g

Density of iron = 8 g/cm

^{3}

Volume of iron used in the alloy = mass of iron / density

= 240/8 = 30 cm

^{3}

Total mass of the alloy = 540 + 240 = 780 g

Total volume of the alloy = 60 + 30 = 90

Density of the alloy = mass of the alloy / density of the alloy = 780 / 90 = 8.67 g/cm

^{3}

## Chapter 1 - Measurement Exercise 49

(a). First of all we find the least count and zero error of the vernier calipers.

(b). Place the object whose length is to be measured below the lower jaws and move the jaw till it touches the object. Record the main reading.

(c). Note the division on the vernier scale that coincides with some division of the main scale. Multiply this number of vernier division with least count. This is vernier scale reading.

(d). Record the observed length by adding the main scale reading and the vernier scale reading. Also, subtract zero error with its proper sign, if any, from the observed length to find the true length of the object.

(a). Calculate the least count and zero error of the screw gauge.

(b). Place the wire in between the studs. Turn the ratchet clockwise so as to hold the wire gently in between the studs. Record the main scale reading.

(c). Now record the division of circular scale that coincides with the base line of main scale. This circular scale division multiplied by least count will give circular scale reading.

(d). The observed diameter is obtained by adding the circular scale reading to the main scale reading. Subtract the zero error if any, with its proper sign, from the observed diameter to get the true diameter.

Precautions to be taken for measuring the length of the object, the eye must be kept vertically above the end of the object to avoid parallax and the corresponding marking along the line should be carefully read.

The meter scale can measure up to an accuracy of 1mm or 0.1 cm

(ii) Amplitude - Amplitude is the magnitude of the maximum deviation of the bob from the mean position on either side when an oscillation takes place.

(iii) Frequency - the number of oscillation made by the pendulum in one second is called frequency. Its SI unit is Hertz (Hz).

(iv) Time period - The time taken by a simple pendulum for an oscillation is known as the time period of a simple pendulum.

## Chapter 1 - Measurement Exercise 50

(i). Before starting, bring the plumb line just above the pointed projection by adjusting the leveling screws at the base. The beam is then gently raised using the lever. And it should be ensured that the pointer swings equally on both sides of the zero mark of the scale.

(ii). Now lower the beam gently and given body is kept on left pan.

(iii). Next, place some weight on the right pan form the weight box using the forceps.

(iv). Now the lever is turned towards right so that the beam rises and the power begins to swing to pointer swing on either side. It must be carefully noted that the side to which the pointer moves more, denotes lesser mass on that side.

(v). Go on adjusting the standard weights till the pointer swings equally on both sides of the zero mark.

(vi). At this stage, the total mass of weights on the right pan gives the mass of the body.

Three precautions to be taken to measure the mass of a body using beam balance are

(a). The beam must be gently lowered before adding or removing weights from the pan.

(b). The weights should not be carried with bare hands to avoid the change in weights due to moisture and dust particles from the surrounding

(c). Whenever you are near the actual weight, you should carefully try the weights in the descending order.

Conditions for a beam balance to be true are

(vii). Both the pans must be of equal weights.

(viii). Both the arms must be of equal lengths.

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