Experiments Questions and Answers

In a specially designed vernier calipers 10 divisions of the vernier scale are equal to 4 divisions of the main scale In the following figure the zero error and a measurement are shown In the zero error the 5th and the 10th divisions of the vernier coincides with 1 mm and 3 mm mark on the main scale respectively and in the measurement the 2nd and the 7th divisions of the vernier scale coincide with the 23 mm and 25 mm mark on the main scale respectively as shown in the figure Report the length measured with due regards to the error Zero Error 0 0 10 1 2 3 4 2 3 antolatul imtadintadigalutintul Reading of Measurement 1 5 0 0 10 4 5

it diagram of metre bridge is shown in figure The null point is found at a distance of 40 cm from A If now a resistance of 120 is connected in parallel with S the null point occu ermine the value of R and S 40 3200 10 3100 110 220 www B OG D A mulut alustall

A projectile is fired horizontally from an inclined plane of inclination 45 with horizontal with speed 50 m s If g 10 m s the range measured along the incline is A 500 m C 200 2 m B 500 2 m D none of these

The position vector of a particle is given as F t 8t 12 i t j The time after which velocity vector and acceleration vector becomes perpendicular to each other is equal to A 1 sec C 2 sec B 2 5 sec D 1 5 sec

A pendulum clock loses 12 s a day if the temperature is 40 C and gains 4 s a day if th temperature is 20 C The temperature at which the clock will show correct time and the c efficient of linear expansion a of the metal of the pendulum shaft are respectively 2016 1 60 C a 1 85 x 10 C 3 55 C a 1 85 x 10 2 C 2 30 C a 1 85 10 C 4 25 C a 1 85 x 10 5 C

5 The time dependence of a physical quantity p is given by p po exp at where a is a constant and t is the time The constant a a is dimensionless b has dimensions T c has dimensions T d has dimensions of p

4 V V fata af 45 f a A ball is thrown at angle of 45 with horizontal 20 and having range R and an other ball is thrown at angle of 60 with horizontal and having range R then which of following is correct statement 1 R R 2 R R 3 Data insufficient 4 R R fare 60fa fa un afara 1 R R 2 R R 3 4 R R St

57 A winch is driven by an electric motor with a separate excitation and fed from a battery of emf 300 V The rope and the hook of the winch rise at a velocity v 4 m s without a load and at a velocity v 1 m s with a load of mass m 10 kg Anode 127V Cathode DE Fig 110 Fig 111 Determine the velocity v of the load and its mass m for which the winch has the maximum power neglecting the mass of the rope and the hook

The universal gravitational constant is measured experimentally using Cavendish s experiment This experiment is a very precise experiment which gives the value of G as 6 6742 0 0010 x 10 11 N m2 kg2 Since the universal gravitational constant has some error in it using it if we find escape speed and acceleration due to gravity on Earth s surface our values will have error in it Assume mass of Earth 6 0000 x 1024 kg radius of Earth 6 4000 10 m The measurement of mass of Earth has an error of 0 01 and radius of Earth has an error of 0 02 What will be the maximum percentage error in calculating the escape speed on earth

4 At time t 0 a tank contains 20 lbs of salt dissolved in 100 gal of water Water containing 1 4 lb of salt gal enters the tank at a rate of 2 gallons per minute and the mixture is well stirred and draining from the tank at the same rate Find the amount of salt Q t in lbs in the tank at any time

A capacitor of capacitance C is connected to two voltmeters A and B A is an ideal voltmeter having infinite resistance while B has resistance R The capacitor is uncharged and then the switch Sis closed at t 0 B So C reading of B and A will be and zero respectively at t 0 during time interval 0 t reading of B and A are changing reading of A and B will be equal at t RC In 2 D None of these

The vernier scale of a callipers has 50 divisions which coincide with 49 main scale divisions If each main scale division is of 0 5 mm then the minimum inaccuracy in the measurement by callipers is 1 0 02 cm 3 0 01 mm LEX 2 0 02 mm 4 0 01 cm

8 Four instruments measured the diameter of a wire whose values are given below Instrument 1 1 3 mm Instrument 2 1 32 mm Instrument 3 1 324 mm Instrument 4 1 03 mm The instrument having smallest value of least count is O a Instrument 1 O b Instrument 2 O c Instrument 3 O d Instrument 4

If a wire having initial diameter of 2 mm produced the longitunal strain of 0 1 then the final diameter of wire is o 0 5 1 2 002 mm 3 1 998 mm 2 1 999 mm 42 001 mm

7 In a specially designed vernier calipers 10 divisions of the vernier scale are equal to 4 divisions of the main scale In the following figure the zero error and a measurement are shown In the zero error the 5th and the 10th divisions of the vernier coincides with 1 mm and 3 mm mark on the main scale respectively and in the measurement the 2nd and the 7th divisions of the vernier scale coincide with the 23 mm and 25mm mark on the main scale respectively as shown in the figure Report the length measured with due regards to the error Zero Error 0 0 10 1 2 3 5 Reading of Measurement 1 2 migh 3 10 4 5

To measure the volume of a cylinderical wir e its diameter is measured by a screw gaug e and is found to be 1 25 mm and its length is measured with a vernier caliper and is fou nd to be 5 50 cm The least count of the scr ew gauge is 0 01 mm and that of the vernie r caliper is 0 01 cm i Percentage error due to area is more than percentage error due to length ii Number of significant figures in volume will be two iii Percentage error in volume will be 1 7 8 iv Percentage error in length is 1 6

Example Two infinite ground metal plates lie parallel to he xz plane one at y 0 the other at y a The Left end at x 0 is closed off with an infinite strip insulated from the two plates and maintained at a specific potential V y Find the potential inside the 2 plates YA V V y Z G A Extends to V 0 V 0 Extends to co X

27 A uniform magnetic field of induction B is confined to a cylindrical region of radius R The magnetic field is dB Ts An electron placed at the point P on the periphery of the field dr increasing at a constant rate of experiences an acceleration 1 eR dB toward left A B 2 m di 1 eR dB 2 m dr eR dB C D zero m dr toward right toward left X X X X X X X X X X X X X P X X X X X

3 7 3n 1 A vessel contains a non linear triatomic gas If 50 of gas dissociate into individual atom then find new va of degree of freedom by ignoring the vibrational mode and any further dissociation 1 2 15 3 5 25 2 3 75 4 6 35

Two block of mass 3 kg and 6 kg respectively are placed on a smooth horizontal surface They are connected by a light spring of force constant k 200 N m Initially the spring is unstretched The indicated velocities are imparted to the blocks The maximum extension of the spring will be A 30 cm C 20 cm B 25 cm D 15 cm 1 0 m s 3 kg mmmm 2 0 m s 6 kg

Q No 15 Optical micrometer is used to A Measure small linear displacements B Measure surface profiles C Measure surface roughness D Set very small displacement by rotating the glass block through relatively large angles

In an experiment the angles are required to be measured using an instrument whose 29 divisions of the main scale exactly coincide with the 30 divisions of the vernier scale If the smallest division of the main scale is half a degree 0 5 then the least count of the instrument is 1 One minute 2 Half minute 3 One degree 1 Half degree

Q No 18 In precision polygon a central hole and small holes are drilled through the thickness A For mounting purposes B To achieve high accuracy C For ease of manufacture D To make them light

Q No 29 Which of the following is the essential condition for interferometry measurement A An air gap a wedge of varying thickness must exist between the two surfaces B Monochromatic source of light is required C The work surface must be reflective D All of the above

gauge least count 001 cm comes out to be 0 802 cm The percentage error in the measurement is 1 0 125 3 4 11 2 2 43 10

Knowledge Sections Q No 4 IS 919 on limits and fits specifies following numbers of grades of fundamental tolerances and fundamental deviations respectively A 25 18 B 25 16 C 18 22 D 18 25

ALLEN CAREER INSTITUT 43 The fig shows the position time graph of a particle moving on a straight line path What is the magnitude of average speed of the particle over 10 seconds x m 60 40 30 20 104 1 2 m s 3 6 m s 44 An ant is scramping 8 10 t s 2 4 m s 4 8 m s on the stairs as shown in

Due to economic reasons only the upper sideband of an AM wave is transmitted but at the receiving station there is a facility for generating the carrier Show that if a device is available which can multiply two signals then it is possible to recover the modulating signal at the receiver station

Q No 8 Eden Roll comparator is a popular equipment for the A Calibration of slip gauges B Absolute measurement of length of slip gauges C Measurement of flatness D Measurement of angles Sections

126 i In the circuit diagram given below AB is a uniform wire of resistance 15 92 and length 1 m It is connected to a cell E of emf 2V and negligible internal resistance and a resistance R The balance point with another cell E of emf 75 mV is found at 30 cm from end A Calculate the value of R A E E 11 X R B

Q No 25 Which of the following is not the essential requirement for accuracy of measurement with a sine bar A Flatness of upper surface B Equality of size and roundness of rollers C Exact distance between roller axes and mutual parallelism D Parallelism between top and bottom surfaces

Q No 15 Surface plate is usually made of grey cast iron because it provides A Non wearing plate B Very hard plate C Easy to cast plate D Lubrication due to graphite flakes

Q No Differential screw micrometer is used A To give direct indication of difference between two readings B For very high degree of accuracy C For digital readout D To measure diameter of inaccessible holes

In a meter bridge the point D is a neutral point Fig 11 3 3 a The meter bridge can have no other neutral point for this set of resistances b When the jockey contacts a point on meter wire left of D current flows to B from the wire When the jockey contacts a point on the meter wire to the right of D current flows from B the wire through galvanometer d When R is increased the neutral point shifts to left A R B S 100 L C

is In the circuit shown assuming all ammeters to be ideal if readings of the hot wire ammeters A and A are i and i respectively then reading of the hot wire ammeter A R A equal to i 1 C less than i 1 AC source B greater than i i D equal to 21 i i

Hol da Fig 3 5 3 20 B While doing an experiment with potentiometer Fig 3 5 it was found that the deflection is one sided and i the deflection decreased while moving from one end A of the wire to the end B ii the deflection increased while the jockey was moved towards the end B i Which terminal or ve of the cell E is connected at X in case i and how is E related to E ii Which terminal of the cell E is connected at X in case ii

Q No 21 Measuring instrument intended to define or present physically conserve or reproduce the unit of measurement of a quantity or a multiple or sub multiple of that unit and to transfer it to other measuring instruments by comparison is known as A Legal measuring standard B Standard Sections C Working standard D Primary standard

Q No 34 A scale whose graduation marks are in a discontinuous manner and are composed of aligned numbers indicating directly the numerical value of the quantity measured is called A Linear scale B Digital scale Knowledge Sections C Equidistant scale D Regular scale 6

0 In the circuit given below V t is the sinusoidal voltage source voltage drop VAB t across the resistance Ris R 100 2 a b c www D ob 100 REV 1061 III bus III s D Ihes II d R 15092 AB V t gniazotoni Son c has the same peak value in the positive and negative half cycles mine hoc different neak values during positive is half wave rectified is full wave rectified

Knowledge Sections Q No 15 Which of the following characterizes the dispersion of the results obtained in a series of measurements of the same value of a quantity measured A Absolute error B Relative error C Root mean square deviation D Uncertainty of measurement

Q No 25 Knowledge Sections Instrument which is designed to eliminate the personal element of feel when setting a measuring instrument is called A Fiducial indicator B Zero setting device C Auxiliary measuring instruments D Measuring standard

5 If the percentage error in the measurement of momentum and mass of an object are 2 and 3 respectively then maximum percentage error in the calculated value of its kinetic energy is 1 2 2 1 3 5 4 7

A clock which keeps correct time at 20 C is subjected to 40 C If coefficient of linear expansion of the pendulum is 12 10 per C how much will it gain or lose in time 1 10 3 seconds day 2 20 6 seconds day 3 5 seconds day 4 20 minutes day

In a slide calliper n divisions of vernier scale coincides with n 1 divisions of main scale The least count of the instrument is 1 1 MSD n 2 1 n l MSD n 3 MSD n l 4 1 2 n MSD

The pitch of screw gauge is 1 mm and its circular scale is divided into 100 divisions When nothing is put between the students the zero of main scale is not seen but when circular scale is rotated by 450 the zero of main scale is just visible and the zero of main scale coincide with the zero of circular scale When a glass plate is placed between the studs The circular scale li s between 18th division of main scale and circular scale reads 34 divisions Then

The least count of a stop watch is 0 2 second The time of 20 oscillations of a pendulum is measured to be 25 seconds The percentage error in the time period is A 16 B 0 8 C 1 8 D 8

26 A physical quantity A is related to four observables 3 a b a b c and d as follows A c d 1 1 errors of measurement in a b c and d are 4 21 The percentage 50 11 and respectively The possible 3 4 2 percentage error in the calculation quantity A is 1 3 2 2

Y In the determination of Young s modulus ald by using Searle s method a wire of length L 2 m an diameter d 0 5 mm is used For a load M 2 5 kg an extension 0 25 mm in the length of the wire i observed Quantities d and are measured using a screw gauge and a micrometer respectively They have th same pitch of 0 5 mm The number of divisions on their circular scale is 100 The contributions to the maximur probable error of the Y measurement Resonance Educating for better tomorrow Page 4 PHYSICS A due to the errors in the measurements of d and are the same B due to the error in the measurement of d is twice that due to the error in the measurement of l C due to the error in the measurement of is twice that due to the error in the measurement of d

The figure below illustrates a stretch of a horizontal road The markers indicate distance along the road separated by 10 m At A a car enters the stretch of road It accelerates uniformly upto point C and then continue moving at constant speed The dots show the position of the car at one second intervals Using the coordinate system shown select the incorrect choice The speed of car at point B is 30 m s The acceleration of car at point D is zero The speed of car at point E is 50 m s O The acceleration of car at point E is 40 m s Car A B 111 C D H R 50m 45 E

A potentiometer is an accurate and versatile device to make electrical measurements of EMF because the method involves a Potential gradients b A condition of no current flow through the galvanometer c A combination of cells galvanometer and resistances d Cells