Electricity measuring equipments Questions and Answers

D In a common base connection the emitter current is 6 28mA and collector current is 6 20 mA Determine the common base DC current gain

Illustration 27 A galvanometer has a resistance of 30 22 and a current of 2 mA is needed to give a full scale deflection What is the resistance needed and how is it to be connected to convert the galvanometer a into a ammeter of 0 3 A range b into a voltmeter of 0 2 V range

A potentiometer wire of length L and resistance 102 is connected in series with a battery of e m f 2 5V and a resistance in its primary circuit The null point corresponding to a cell of e m f IV is L obtained at a distance If the resistance in the primary circuit is doubled then the position of new 2 null point will be

7 6 Two long current ca plane as shown in the figure Magnitude of net magnetic field at centre point O is Radius of circular parts is R L 1 3 Ho 3 0 4 R Ho 4 0 k k 20 10 2 21 Ho 4 0 k 4t R 4 Zero

4 When two resistances X and Y are put in the left hand and right hand gaps in a wheatstone meter bridge the null point is at 60cm If X is shunted by a resistance equal to half of itself then find the shift in the null point a 26 7 cm b 36 7 cm c 46 7 cm d 96 7 cm

A capacitor is charged by a battery The battery is removed and another identical uncharged capacitor is connected in parallel The total electrostatic energy of resulting system NEET 2017 1 decreases by a factor of 2 times 3 increases by a factor of 2 times 2 remains the same 4 increases by a factor of 4 times or of an isolated parallel plate capacitor C having a charge Q and area A

The emitter base junction of a transistor is biased Question Type Single Correct Type 1 Reverse forward Reverse reverse biased while the collector base junction is

A three stage amplifier has a first stage voltage gain of 100 second stage voltage gain of 200 and third stage voltage gain of 400 Find the total voltage gain in dB Note answer must have decimal point upto 2 decimal e g if answer is 20 you can write it as 20 00

P In the circuit shown R R 10 0 and resistance per unit length of wire PQ 10 cm and length PQ 10 cm If R is made 200 then to get zero deflection in galvanometer S is midpoint of wire PQ R RI 12VT S Q The jockey at P can be moved towards right 3 cm The jockey at Q can be moved towards left 2 cm The jockey at S can be moved towards left a distance 5 3 cm

1 A cell a resistor a key and ammeter are arranged as shown in the circuit diagrams of Figure12 1 The current recorded in the ammeter will be R A R R www ii Fig 12 1 a maximum in i b maximum in ii c maximum in iii d the same in all the cases CK A A K iii

A particle A of mass m and charge Q moves directly towards a fixed particle B which has charge Q The speed of A is a V when it is far away from B The minimum separation between the particles is not proportional to

A galvanometer of resistance 3092 is connected to a battery of emf 2V with 1970 resistance in series A full scale deflection of 20 divisions is obtained in the galvanometer To reduce the deflection to 10 divisions the resistance in series required is 2 Points 3970 ohms 2000 ohms 4000 ohms 4030 ohms

5 Alternating current cannot be measured by DC ammeter because becau 1 average value of current for complete cycle is zero 2 AC changes direction 3 AC cannot pass through DC ammeter 4 DC ammeter will be smaller than AC

In the given circuit a charge of 80 C is given to the left plate of 4 F capacitor Then in steady state energy stored inside 2 F capacitor will be 2 F 80 C 4 F 100 J 200 J 150 J 3 F

103 A voltmeter of 998 ohms resistance is connected to a cell of emf 2 volts having internal resistance of 2 ohms The error in measuring emf will be 1 4 x 10 V 2 2 10 V 13 4 x 10 V 4 2 10 V

3 Resistances A and B are connected respectively in the left gap and right 1 point gap of a metre bridge If the balance point is located at 55 cm from the right the ratio A B is a 4 5 b 5 4 c 9 11 d 11 9

6 Indicate the wrong statement from the following For accurate measurements a potentiometer wire Oa must have a uniform cross section Ob must have a high temperature coefficient of resistance Oc high specific resistance Od homogeneity

A micro ammeter has a resistance of 10002 and 42 full scale range of 50 A It can be used as a voltmeter or as a higher range ammeter provided a resistance is added to it Pick the correct range and resistance combination 1 50 V range with 10k2 resistance in series 2 5 mA range with 12 resistance in parallel 3 10 mA range with 10 resistance in parallel 4 none of these 50 g ad at sa atcete if y fauna 1000 of factu faits fear and fe 1 10k 2 HHI H 10 xe i HII 5 mA TTH 3 110 mA 4

5 Meter Bridge is device based on wheatstone bridge with resistances connnected in a particular fashion It can be used to obtain unknown resistance One of the resistance wire used is of 1 m length giving its name A jockey is used to obtain the neutral position diving the circuit in two parts 1 Draw a inducative diagram representing above detail of meter bridge ii Can a meter bridge be made with 2 m long wire instead of 1 m iii Which device is connected to jockey to detect the flow of current and obtain neutral point iv If neutral point is mid way and standard resistance used is 10 2 then what is the value of unknown resistance V What can we conclude if we don t get any neutral point 2 1 2 1 2 1 1

In given meter bridge circuit length of wire AB is 1m When resistance X is shunted by R resistance then balancing length from A is found to be 20 cm Find value of R A X 69 ww C r 32 www 6 B Question Type Single Correct Type

A vernier calipers and a screw gauge have the same least count and zero error with the difference that the vernier calipers has positive zero error and the screw gauge has negative zero error The number of circular scale divisions on the screw gauge is twice the number of vernier scale divisions on the vernier calipers and the pitch of the screw gauge is 1 mm If the vernier coinciding division and the circular scale reading for the zero error on the instruments are 3 and 97 respectively then find the number of vernier scale divisions on the vernier

The current supplied to an air conditioner unit is 7 02 amps The air conditioner is wired using a 10 gauge diameter 2 588 mm wire The charge density is n 8 48 x 1028 electrons m Find th following magnitudes a current density in A m A m b the drift velocity in m s m s

Figure shows a balanced wheatstone bridge The value of Ris 100 Q A ww 200 2 20 22 25 22 40 22 15 22 100 2 D E www 40 Q2

In an experiment to determine the resistance of a galvanometer by half deflection method the circuit shown is used In one set of reading R102 and S4 02 then the resistance of the galvanometer is mathongo mathol A 20 C mathongo athongo mathongo mathong B Q D 7 mathongo mathongo mathongo mathongs 2 13 pm

NEET Full Course Material Two cells of emfs E and E E E are connected as shown in figure a 3 1 2 3 When a potentiometer is connected between A and B then the balancing length of the potentiometer wire is 300 cm On connecting the same potentiometer between A and C the A E balancing length is 100 cm The ratio potentiometer experimar tion when a B b 1 3 d 3 2 E HTC E is E

2 A metal rod of length 10 cm and a rectangular cross section of 1 cm x cm is connected to a battery across opposite faces The resistance will be a maximum when the battery is connected across 1cm x1 2 cm faces b maximum when the battery is connected across 10cm x1 cm faces c maximum when the battery is connected across 10 cm x1 2 cm faces d same irrespective of three faces

Consider a circuit shown in the figure The switch S is closed at t 0 Find the currents as a function of time through a the inductor and b the battery 192 352 5251 1H 40

In the given circuit resistance of potentiometer wire AB is 1022 and its length is Im Rest of quantities are shown in figure The null point will be at a separation m from point A then find value of x 8 3 1 5v 0 30 ww 1 20 1502 www B

A microammeter has a resistance of 100W and a full scale range of 50 A It can be used as a voltmeter or a higher range ammeter provided a resistance is added to it Pick the correct range and resistance combination s 1 10V range with 200 kW resistance in series 2 50V range with 10 kW resistance in series 3 5 mA range with 1W resistance in parallel 4 10 mA range with 1 kW resistance in parallel

b Describe the various type of torques present in the measuring instruments their type and how they are produced 5 5 5 a A long shunt compound generator delivers a load of 50 A at 500V and the resistances of armature series field and shunt field are 0 05 2 0 03 2 and 250 2 respectively Calculate the generated e m f and the armature current Allow 1 0 V per brush for contact drop

In the Wheatstone s network given P 10 2n Q 20 22 R 15 Q2 S 30 2 The current passing through the battery of negligible internal resistance is A 0 36 A 0 A B C 0 18 A D 0 72 A P www G www Q R 1 www ww S

The emf of the cell is 2V and its internal resistance is 2 ohm A resistance of 8 ohm is joined to the battery in parallel This is connected is the secondary circuit of the potentiometer If 1V standard cell balances for 100 cm of potentiometer wire the balance point of the above cell is A B D 120 cm 240 cm 160 cm 116 cm

52 A potentiometer having the potential gradient of 2 mV cm is used to measure the difference of If a length of 50 cm of the potentiometer wire is potential across a resistance of 10Q in same circuit required to get the null point then the current passing through the 10 resistor is in mA a 1 b 2 c 5 d 10 The

A galvanometer may be converted voltmeter following cases the resistance of the device so obtained will be the largest in to ammeter or a In which of the O Voltmeter of range 10V O Ammeter of range 10 A O Voltmeter of range 1V ammeter of range 1 A 1 pc

In potentiometer balancing length of first cell and second cell is 2 m and 1 5 m respectively when they are connected separately Hence E1 E2 is a 0 8 b 1 c 1 1 d 1 25 O 1 33 O 1 25 experiment 2 points 0 75 O 0 8

The rime of 50 cm diameter wheel on a brake shoe testing machine has a speed of 16 5 m s when the break is applied It comes to rest after the rim has traveled a liner distance of 600 m What is the constant angular acceleration of the wheel and how many revolutions does it make after the break is applied Ans a 0 8 rad s2 deceleration N 382 revolution

The maximum current that can flow through a galvanometer is 5 mA If the galvanometer has to be converted into an ammeter of range 0 10 A which of the following would be preferred Resistance of galvanometer 100 1 0 00502 in parallel with galvanometer 2 0 00502 in series with galvanometer 3 500002 in parallel with galvanometer 4 500002 in series with galvanometer

45 In the situation shown what is the value of resistance between A and D in addition to 12 resistance so that galvanometer shows no deflection connected A 1 12 2 3 42 10 22 ww www 1202 D 5002 ww www 2002 2 692 4 50 B

Wheatstone Network R D A VG C B f R1 3ohm R2 5 ohm R3 10 ohm resistor shunted with 10 ohm resistor the value Rx is Mark only one oval Rx 3 ohm Rx 15 ohm Rx 25 ohm

introduce a cylindrical soff iron core inside the coil of a galvanometer 17 Write the factors on which the sensitivity of a moving coil galvanometer depends Nam material used in the suspension wire of a MCG Justify your answer

When two coils are connected in series their effective inductance is found to be 10H however when connections to one coil is reversed the effective inductance If coefficient of coupling is 0 6 Calculate the difference in self inductance of each coil

The EMF of a standard cell is balanced over a 150 cm length of a potentiometer wire When this cell is shunted by a 292 resistance the null point is obtained at 100 cm The value of internal resistance of the cell is 1 0 12 3 292 2 122 4 0 592

A 6V battery of negligible internal resistance is connected across a uniform wire AB of length 100 cm The positive terminal of another battery of emf 4 V and internal resistance 1 Q is joined to the point A as shown in figure If galvanometer shows zero deflection then 6 V A H HWW G 4V 12 B

For a transistor amplifier the voltage gain in CE configuration Remains constant for all frequencies Is low at low and high frequencies and constant for mid frequencies Is low at low frequency high at high frequencies and constant for mid frequencies Constant at low and high frequencies and low at mid frequencies

In the Fig 2 69 AB is a potentiometer wire of length 50 cm and resistance 1 The emf of the source of elec tricity E is 24 V and its internal resistance in negligibly small A resistance R 15 2 is connected in the circuit If an electric cell E is connected between A and C with a galvanometer G in series with it then for AC 36 cm R AM E 1 C www G www B

R N N K The circuit diagram shown above is used for a Determination of un known emf of a cell b Comparison of emfs of two cells c Determination of unknown resistance d Determination of internal resistance of a cell

In a metre bridge experiment a null point is obtained at a length of 39 8 cm when a 2 resistance is placed in the left gap and a 3 resistance in the right gap If the two resistances are interchanged the null point is obtained at 60 8 cm Calculate the end errors of the bridge

The variation of potential difference V with length 1 in case of two potentiometers X and Y is shown in the figure Which one of the two will you prefer for com paring emfs of the two cells and why VA X Y

Three short electric dipoles each of dipole moment P are placed at the vertices of an equilateral triangle of side length L Each dipole has its moment oriented parallel to the opposite side of the triangle as shown in the fig The electric field strength at the centroid o Then value of a is the triangle is a KP L P L P L L P

The galvanometer shown in figure has resistance 50 Main current of 6 A passes in circuit as shown If current through galvanometer is Ig then 6 A lg 11 10 5 4 2 www wwww 102 5 V S A when switch S is closed Ig A when switch S is closed 15 Ig A when switch S is open lg 0 A when switch S is open