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Students have checked the complete Class 11 Physics Lab Manual in pdf for a great score in the final examination. Pooja Roy is a Senior Content Developer and also handles Edufever School with a mission to make education accessible to all.

Notify me via e-mail if anyone answers my comment. Full Name. Mobile Number. Summary 2. Click Here. Class 11 Free E-Book. To plot a graph for a given set of data choosing proper scale and show error bars due to the precision of the instruments.

To measure the force of limiting rolling friction for a roller wooden block on a horizontal plane. Their basics will become solid as they will learn by doing things. By doing this activity they will also get generated their interest in the subject. Students will develop questioning skills and start studying from a scientific perspective. Get Free Study materials For all classes. To Build Basics Stronger and Bolder. Sign in with Google. Checked checkbox. Create your account. Sign Up with Google.

While calculating the slope, always choose the x-segment of sufficient length and see that it represents a round number of the variable. The corresponding interval of the variable on y-segment is then measured and the slope is calculated. Generally, the slope should not have more than two significant digits. The values of the slope and the intercepts, if there are any, should be written on the graph paper.

Do not show slope as tan. Only when scales along both the axes are identical slope is equal to tan. Also keep in mind that slope of a graph has physical significance, not geometrical.

Often straight-line graphs expected to pass through the origin are found to give some intercepts. Hence, whenever a linear relationship is expected, the slope should be used in the formula instead of the mean of the ratios of the two quantities. However, it is not true for a curve. As shown in Fig. Therefore, in case of a non-straight line curve, we talk of the slope at a particular point. The slope of the curve at a particular point, say point A in Fig.

As such, in order to find the slope of a curve at a given point, one must draw a tangent to the curve at the desired point. In order to draw the tangent to a given curve at a given point, one may use a plane mirror strip attached to a wooden block, so that it stands perpendicular to the paper on which the curve is to be drawn. This is illustrated in Fig. The plane mirror strip MM is placed at the desired point A such that the image DA of the part DA of the curve appears in the mirror strip as continuation of.

In general, the image D A will not appear to be smoothly joined with the part of the curve DA as shown in Fig. Next rotate the mirror strip MM, keeping its position at point A fixed. The image D in the mirror will also rotate. Draw the line MAM along the edge of the mirror for this setting. The slope of the tangent GAH i. The above procedure may be followed for finding the slope of any curve at any given point. The students should thoroughly understand the principle of the experiment.

The objective of the experiment and procedure to be followed should be clear before actually performing the experiment. The apparatus should be arranged in proper order. To avoid any damage, all apparatus should be handled carefully and cautiously.

Any accidental damage or breakage of the apparatus should be immediately brought to the notice of the concerned teacher. Precautions meant for each experiment should be observed strictly while performing it. Repeat every observation, a number of times, even if measured value is found to be the same. The student must bear in mind the proper plan for recording the observations. Recording in tabular form is essential in most of the experiments.

Calculations should be neatly shown using log tables wherever desired. The degree of accuracy of the measurement of each quantity should always be kept in mind, so that final result does not reflect any fictitious accuracy. The result obtained should be suitably rounded off. Wherever possible, the observations should be represented with the help of a graph. Always mention the result in proper SI unit, if any, along with experimental error.

The following heads may usually be followed for preparing the report:. Also, write the formula used, explaining clearly the symbols involved derivation not required.

Mention clearly, on the top of the observation table, the least counts and the range of each measuring instrument used. However, if the result of the experiment depends upon certain conditions like temperature, pressure etc.

Calculate experimental error. Wherever possible, use the graphical method for obtaining the result. Also mention the physical conditions like temperature, pressure etc. Also mention any special inferences which you can draw from your observations or special difficulties faced during the experimentation.

These may also include points for making the experiment more accurate for observing precautions and, in general, for critically relating theory to the experiment for better understanding of the basic principle involved. A Vernier Calliper has two scalesone main scale and a Vernier scale, which slides along the main scale. The main scale and Vernier scale are divided into small divisions though of different magnitudes.

The main scale is graduated in cm and mm. It has two fixed jaws, A and C, projected at right angles to the scale. The sliding Vernier scale has jaws B, D projecting at right angles to it and also the main scale and a metallic strip N. The zero of main scale and Vernier scale coincide when the jaws are made to touch each other.

Knob P is used to slide the vernier scale on the main scale. Screw S is used to fix the vernier scale at a desired position. The least count of a common scale is 1mm. It is difficult to further subdivide it to improve the least count of the scale. A vernier scale enables this to be achieved. Keep the jaws of Vernier Callipers closed.

Observe the zero mark of the main scale. It must perfectly coincide with that of the vernier scale. If this is not so, account for the zero error for all observations to be made while using the instrument as explained on pages Look for the division on the vernier scale that coincides with a division of main scale. Use a magnifying glass, if available and note the number of division on the Vernier scale that coincides with the one on the main scale.

Position your eye directly over the division mark so as to avoid any parallax error. Gently loosen the screw to release the movable jaw. The jaws should be perfectly perpendicular to the diameter of the body. Now, gently tighten the screw so as to clamp the instrument in this position to the body.

Carefully note the position of the zero mark of the vernier scale against the main scale. Usually, it will not perfectly coincide with. Record the main scale division just to the left of the zero mark of the vernier scale. Start looking for exact coincidence of a vernier scale division with that of a main scale division in the vernier window from left end zero to the right. Note its number say N, carefully. Multiply 'N' by least count of the instrument and add the product to the main scale reading noted in step 4.

Ensure that the product is converted into proper units usually cm for addition to be valid. Repeat steps to obtain the diameter of the body at different positions on its curved surface.

Take three sets of reading in each case. Record the observations in the tabular form [Table E 1. Apply zero correction, if need be. Find the arithmetic mean of the corrected readings of the diameter of the body. Express the results in suitable units with appropriate number of significant figures.

Measure the length of the rectangular block if beyond the limits of the extended jaws of Vernier Callipers using a suitable ruler. Otherwise repeat steps described in a after holding the block lengthwise between the jaws of the Vernier Callipers.

Repeat steps stated in a to determine the other dimensions breadth b and height h by holding the rectangular block in proper positions. Record the observations for length, breadth and height of the rectangular block in tabular form [Table E 1. Apply zero corrections wherever necessary. Find out the arithmetic mean of readings taken for length, breadth and height separately.

Adjust the upper jaws CD of the Vernier Callipers so as to touch the wall of the beaker from inside without exerting undue pressure on it. Tighten the screw gently to keep the Vernier Callipers in this position. Do this for two different angular positions of the beaker.

Keep the edge of the main scale of Vernier Callipers, to determine the depth of the beaker, on its peripheral edge. This should be done in such a way that the tip of the strip is able to go freely inside the beaker along its depth.

Keep sliding the moving jaw of the Vernier Callipers until the strip just touches the bottom of the beaker. Take care that it does so while being perfectly perpendicular to the bottom surface.

Now tighten the screw of the Vernier Callipers. Repeat steps 4 to 6 of part a of the experiment to obtain depth of the given beaker. Take the readings for depth at different positions of the breaker. Record the observations in tabular form [Table E 1. Apply zero corrections, if required. Find out the mean of the corrected readings of the internal diameter and depth of the given beaker.

Express the result in suitable units and proper significant figures. If it is not so, the instrument is said to possess zero error e. Zero error may be. This is shown by the Fig. In this situation, a correction is required to the observed readings. From the figure, one can see that when both jaws are touching each other, zero of the vernier scale is shifted to the right of zero of the main scale This might have happened due to manufacturing defect or due to rough handling.

This situation makes it obvious that while taking measurements, the reading taken will be more than the actual reading. Hence, a correction needs to be applied which is proportional to the right shift of zero of vernier scale.

In ideal case, zero of vernier scale should coincide with zero of main scale. But in Fig. From this figure, one can see that when both the jaws are touching each other, zero of the vernier scale is shifted to the left of zero of the main scale.

This situation makes it obvious that while taking measurements, the reading taken will be less than the actual reading. Hence, a correction needs to be applied which is proportional to the left shift of zero of vernier scale.

In Fig. Note that the zero error in this case is considered to be negative. For any measurements done, the negative zero error, 0. Main Scale No. Main Scale Number of No. Table E 1. Screw the vernier tightly without exerting undue pressure to avoid any damage to the threads of the screw. Keep the eye directly over the division mark to avoid any error due to parallax. Note down each observation with correct significant figures and units.

A Vernier Callipers is necessary and suitable only for certain types of measurement where the required dimension of the object is freely accessible. It cannot be used in many situations. If the diameter d is small - say 2 mm, neither the diameter nor the depth of the hole can be measured with a Vernier Callipers. It is meaningless to use it where precision in measurement is not going to affect the result much.

One can undertake an exercise to know the level of skills developed in making measurements using Vernier Callipers. How does a vernier decrease the least count of a scale.

Find the least count of the vernier. How would the precision of the measurement by Vernier Callipers be affected by increasing the number of divisions on its vernier scale? How can you find the value of using a given cylinder and a pair of Vernier Callipers?

Ratio of circumference to the diameter D gives. How can you find the thickness of the sheet used for making of a steel tumbler using Ver nier Callipers? AIM Use of screw gauge to a measure diameter of a given wire, b measure thickness of a given sheet; and c determine volume of an irregular lamina.

More accurate measurement of length, up to 0. As such a Screw Gauge is an instrument of higher precision than a Vernier Callipers. You might have observed an ordinary screw [Fig E2. There are threads on a screw. The separation between any two consecutive threads is the same. The screw can be moved backward or forward in its nut by rotating it antiFig. The distance advanced by the screw when it makes its one complete rotation is the separation between two consecutive threads.

This distance is called the Pitch of the screw. It is usually 1 mm or 0. It has a screw S which advances forward or backward as one rotates the head C through rachet R. There is a linear. The smallest division on the linear scale is 1 mm in one type of screw gauge. There is a circular scale CS on the head, which can be rotated. There are divisions on the circular scale. When the end B of the screw touches the surface A of the stud ST, the zero marks on the main scale and the circular scale should coincide with each other.

In case this is not so, the screw gauge is said to have an error called zero error. Here, the zero mark of the LS and the CS are coinciding with each other. When the reading on the circular scale across the linear scale is more than zero or positive , the instrument has Positive zero error as shown in Fig.

When the reading of the circular scale across the linear scale is less than zero or negative , the instrument is said to have negative zero error as shown in Fig. For example, the linear scale reading as shown in Fig. The division of circular scale which coincides with the main scale line is the reading of circular scale. For example, in the Fig.

The linear distance moved by the screw when it is rotated by one division of the circular scale, is the least distance that can be measured accurately by the instrument. It is called the least count of the instrument. For example for a screw gauge with a pitch of 1mm and divisions on the circular scale. In another type of screw gauge, pitch is 0. The least count of this screw gauge is 0.

Note that here two rotations of the circular scale make the screw to advance through a distance of 1 mm. Some screw gauge have a least count of 0. Take the screw gauge and make sure that the rachet R on the head of the screw functions properly.

Rotate the screw through, say, ten complete rotations and observe the distance through which it has receded. This distance is the reading on the linear scale marked by the edge of the circular scale. Then, find the pitch of the screw, i. Insert the given wire between the screw and the stud of the screw gauge.

Move the screw forward by rotating the rachet till the wire is gently gripped between the screw and the stud as shown in Fig. Stop rotating the rachet the moment you hear a click sound. Take the readings on the linear scale and the circular scale. From these two readings, obtain the diameter of the wire.

The wire may not have an exactly circular cross-section. For this, first record the reading of diameter d1 [Fig. Record the reading for diameter d2 in this position [Fig.

The wire may not be truly cylindrical. Therefore, it is necessary to measure the diameter at several different places and obtain the average value of diameter. For this, repeat the steps 3 to 6 for three more positions of the wire. Take the mean of the different values of diameter so obtained.

Substract zero error, if any, with proper sign to get the corrected value for the diameter of the wire. Least Count L. Reading along perpendicular direction d2 Linear scale reading M mm. Rachet arrangement in screw gauge must be utilised to avoid undue pressure on the wire as this may change the diameter.

Reading should be taken atleast at four different points along the length of the wire. View all the reading keeping the eye perpendicular to the scale to avoid error due to parallax. However, with repeated use, the threads of both the screw and the nut may get worn out.

As a result a gap develops between these two threads, which is called play. The play in the threads may introduce an error in measurement in devices like screw gauge. This error is called backlash error. In instruments having backlash error, the screw slips a small linear distance without rotation. To prevent this, it is advised that the screw should be moved in only one direction while taking measurements.

The divisions on the linear scale and the circular scale may not be evenly spaced. Try to assess if the value of diameter obtained by you is realistic or not. There may be an error by a factor of 10 or You can obtain a very rough estimation of the diameter of the wire by measuring its thickness with an ordinary metre scale. Why does a screw gauge develop backlash error with use? Is the screw gauge with smaller least count always better?

If you are given two screw gauges, one with divisions on circular scale and another with divisions, which one would you prefer and why? Is there a situation in which the linear distance moved by the screw is not proportional to the rotation given to it?

Is it possible that the zero of circular scale lies above the zero line of main scale, yet the error is positive zero error? For measurement of small lengths, why do we prefer screw gauge over Vernier Callipers?

Compare the pitch of an ordinary screw with that of a screw guage. In what ways are the two different? Measure the diameters of petioles stem which holds the leaf of different leaf and check if it has any relation with the mass or surface area of the leaf. Let the petiole dry before measuring its diameter by screw gauge. Measure the thickness of the sheet of stainless steel glasses of various make and relate it to their price structure. Measure the pitch of the screw end of different types of hooks and check if it has any relation with the weight each one of these hooks are expected to hold.

Measure the thickness of different glass bangles available in the Market. Are they made as per some standard?

Collect from the market, wires of different gauge numbers, measure their diameters and relate the two. Find out various uses of wires of each gauge number.

Insert the given sheet between the studs of the screw gauge and determine the thickness at five different positions. Find the average thickness and calculate the correct thickness by applying zero error following the steps followed earlier. Error due to backlash though can be minimised but cannot be eliminated completely. Assess whether the thickness of sheet measured by you is realistic or not.

You may take a pile of say 20 sheets, and find its thickness using a metre scale and then calculate the thickness of one sheet. What are the limitations of the screw gauge if it is used to measure the thickness of a thick cardboard sheet? Find out the thickness of different wood ply boards available in the market and verify them with the specifications provided by the supplier.

Measure the thickness of the steel sheets used in steel almirahs manufactured by different suppliers and compare their prices. Is it better to pay for a steel almirah by mass or by the guage of steel sheets used?

Hold 30 pages of your practical notebook between the screw and the stud and measure its thickness to find the thickness of one sheet.

Find the thickness of lamina as in Experiment E 2 b. Place the irregular lamina on a sheet of paper with mm graph. Draw the outline of the lamina using a sharp pencil. Count the total number of squares and also more than half squares within the boundary of the lamina and determine the area of the lamina. Obtain the volume of the lamina using the relation mean thickness area of lamina.

The first section of the table is now for readings of thickness at five different places along the edge of the. Calculate the mean thickness and make correction for zero error, if any. From the outline drawn on the graph paper:Total number of complete squares. To determine the radius of curvature of a given spherical surface by a spherometer.

A spherometer consists of a metallic triangular frame F supported on three legs of equal length A, B and C Fig. The lower tips of the legs form three corners of an equilateral triangle ABC and lie on the periphery of a base circle of known radius, r. The spherometer also consists of a central leg OS an accurately cut screw , which can be raised or lowered through a threaded hole V nut at the centre of the frame F.

The lower tip of the central screw, when lowered to the plane formed by the tips of legs A, B and C touches the centre of triangle ABC. The central screw also carries a circular disc D at its top having a circular scale divided into or equal parts.

A small vertical scale P marked in millimetres or half-millimetres, called main scale is also fixed parallel to the central screw, at one end of the frame F. This scale P is kept very close to the rim of disc D but it does not touch the disc D. This scale reads the vertical distance which the central leg moves through Fig. This scale is also known as pitch scale.

Commonly used spherometers in school laboratories have graduations in millimetres on pitch scale and may have equal divisions on circular disc scale. In one rotation of the circular scale, the central screw advances or recedes by 1 mm. Thus, the pitch of the screw is 1 mm. Least Count: Least count of a spherometer is the distance moved by the spherometer screw when it is turned through one division on the circular scale, i.

The least count of commonly used spherometers is 0. However, some spherometers have least count as small as 0. Points A and B are the positions of the two spherometer legs on the given spherical surface. The position of the third spherometer leg is not shown in Fig.

The point O is the point of contact of the tip of central screw with the spherical surface. From this figure, it can be noted that the point M is not only the mid point of line AB but it is the centre of base circle and centre of the equilateral triangle ABC formed by the lower tips of the legs of the spherometer Fig. This distance OM is also called sagitta. Let this be h.

It is known that if two chords of a circle, such as AB and OZ, intersect at a point M then the areas of the rectangles described by the two parts of chords are equal.

Then AM. Now, let l be the distance between any two legs of the spherometer or the side of the equilateral triangle ABC Fig. Note the value of one division on pitch scale of the given spherometer. Note the number of divisions on circular scale. Determine the pitch and least count L.

Place the given flat glass plate on a horizontal plane and keep the spherometer on it so that its three legs rest on the plate. Place the spherometer on a sheet of paper or on a page in practical note book and press it lightly and take the impressions of the tips of its three legs.

Calculate the mean distance between two spherometer legs, l. In the determination of radius of curvature R of the given spherical surface, the term l 2 is used see formula used. Therefore, great care must be taken in the measurement of length, l. Place the given spherical surface on the plane glass plate and then place the spherometer on it by raising or lowering the central screw sufficiently upwards or downwards so that the three spherometer legs may rest on the spherical surface Fig.

Rotate the central screw till it gently touches the spherical surface. To be sure that the screw touches the surface one can observe its image formed due to reflection from the surface beneath it.

Take the spherometer reading h 1 by taking the reading of the pitch scale. Also read the divisions of the circular scale that is in line with the pitch scale. Record the readings in Table E 3. Remove the spherical surface and place the spherometer on plane glass plate. Turn the central screw till its tip gently touches the glass plate. Take the spherometer reading h 2 and record it in Table E 3. The difference between h 1 and h 2 is equal to the value of sagitta h.

Repeat steps 5 to 8 three more times by rotating the spherical surface leaving its centre undisturbed. Find the mean value of h. Using the values of l and h, calculate the radius of curvature R from the formula:. Parallax error while reading the pitch scale corresponding to the level of the circular scale.

Backlash error of the spherometer. Non-uniformity of the divisions in the circular scale. While setting the spherometer, screw may or may not be touching the horizontal plane surface or the spherical surface. The most commonly used two-pan beam balance is an application of a lever.

It consists of a rigid uniform bar beam , two pans suspended from each end, and a pivotal point in the centre of the bar Fig.

At this pivotal point, a support called fulcrum is set at right angles to the beam. This beam balance works on the principle of moments. For high precision measurements, a physical balance Fig. Like a common beam balance, a physical balance too consists of a pair of scale pans P1 and P2, one at each end of a rigid beam B. The pans P1 and P2 are suspended through stirrups S1 and S2 respectively, on inverted knife-edges E 1 and E2, respectively, provided symmetrically Fig.

The beam is also provided with a hard material like agate knifeedge E fixed at the centre pointing downwards and is supported on a vertical pillar V fixed on a wooden baseboard W.

The baseboard is provided with three levelling screws W1, W2 and W3. In most balances, screws W1 and W2 are of adjustable heights and through these the baseboard W is levelled horizontally. The third screw W3, not visible in Fig.

When the balance is in use, the Thus, the central edge E acts as a pivot or fulcrum for the beam B. When the balance is not in use, the beam rests on the supports X 1 and X 2, These supports, X 1 and X 2, are fixed to another horizontal bar attached with the central pillar V. In some balances, supports Al and A2 are not fixed and in that case the pans rest on board W, when the balance is not in use.

At the centre of beam B, a pointer P is also fixed at right angles to it. A knob K, connected by a horizontal rod to the vertical pillar V, is also attached from outside with the board W. With the help of this knob, the vertical pillar V and supports A1 and A2 can be raised or lowered simultaneously. Thus, at the 'ON' position of the knob K, the beam B also gets raised and is then suspended only by the knife-edge E and oscillates freely.

Along with the beam, the pans P1 and P2 also begin to swing up and down. This oscillatory motion of the beam can be observed by the motion of the pointer P with reference to a scale G provided at the base of the pillar V.

In the 'OFF' position of the knob K, the entire balance is said to be arrested. Such an arresting arrangement protects the knife-edges from undue wear and tear and injury during transfer of masses unknown and standards from the pan. On turning the knob K slowly to its ON position, when there are no masses in the two pans, the oscillatory motion or swing of the pointer P with reference to the scale G must be same on either side of the zero mark on G.

And the pointer must stop its oscillatory motion at the zero mark. It represents the vertical position of the pointer P and horizontal position of the beam B. However, if the swing is not the same on either side of the zero mark, the two balancing screws B1 and B2 at the two ends of the beam are adjusted.

The baseboard W is levelled horizontal1y to make the pillar V vertical. This setting is checked with the help of plumb line R suspended by the side of pillar V. The appartus is placed in a glass case with two doors. For measuring the gravitational mass of an object using a physical balance, it is compared with a standard mass. A set of standard masses g, 50 g, 20 g, 10g, 5 g, 2 g, and 1 g along with a pair of forceps is contained in a wooden box called Weight Box. The masses are arranged in circular grooves as shown in Fig.

A set of milligram masses mg, mg, mg, 50 mg, 20 mg 10 mg, 5 mg, 2 mg, and 1 mg is also kept separately in the weight box.

A physical balance is usually designed to measure masses of bodies up to g. In a balance, the two arms are of equal length and the two pans are also of equal masses. When the pans are empty, the beam remains horizontal on raising the beam base by using the lower knob. When an object to be weighed is placed in the left pan, the beam turns in the anticlockwise direction. Equilibrium can be obtained by placing suitable known standard weights on the right hand pan.

Since, the force arms are equal, the weight i. A physical balance compares forces. The forces are the weights mass acceleration due to gravity of the objects placed in the two pans of the physical balance. Since the weights are directly proportional to the masses if weighed at the same place, therefore, a physical balance is used for the comparison of gravitational masses.

Examine the physical balance and recognise all of its parts. Check that every part is at its proper place. Check that set of the weight, both in gram and milligram, in the weight box are complete.

Ensure that the pans are clean and dry. Check the functioning of arresting mechanism of the beam B by means of the knob K. Level the wooden baseboard W of the physical balance horizontally with the help of the levelling screws W1 and W2. In levelled position, the lower tip of the plumb line R should be exactly above the fixed needle point N.

Use a spirit level for this purpose. Close the shutters of the glass case provided for covering the balance and slowly raise the beam B using the knob K. Observe the oscillatory motion of the pointer P with reference to the small scale G fixed at the foot of the vertical pillar V. In case, the pointer does not start swinging, give a small gentle jerk to one of the pans. Fix your eye perpendicular to the scale to avoid parallax.