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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 901. |
For driving a current of 2 A for 6 minutes in a circuit, 1000 J of work is to be done. The e.m.f. of the source in the circuit isA. `1.38V`B. `1.68V`C. `2.04V`D. `3.10V` |
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Answer» Correct Answer - A |
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| 902. |
Emf if most closely related toA. Mechanical forceB. Potenital differenceC. Electric fieldD. Magnetic field |
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Answer» Correct Answer - B |
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| 903. |
The potential difference between point A & B is A. `(20)/(7)V`B. `(40)/(7)V`C. `(10)/(7)V`D. 0 |
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Answer» Correct Answer - D |
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| 904. |
To get maximum current through a resistance of `2.5Omega,` one can use m rows of cells, each row having n cells. The internal resistance of each cell is `0.5 Omega` what are the values of n and m, if the total number of cells is 45.A. m=3, n=15B. m=5,n=9C. m=9, n=5D. m=15, n=3 |
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Answer» Correct Answer - A The current l will be maximum, if if `" " mR=nr` or `R=(nr)/(m)` Here, mn = 45 `" "` (given) …(i) and `m xx 2.5=n xx0.5` or n = 5 m …(ii) From Eqs. (i) and (ii), we have `5m^(2)=45` or `m^(2)=9 rArr m =3` `therefore " " n = 15` |
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| 905. |
In the circuit shown below. The reading of the voltmeter V is A. 12VB. 8VC. 20VD. 16V |
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Answer» Correct Answer - A |
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| 906. |
To get a maximum current through a resistance of `2.5Omega` one can use m rows of cells each row having n cells . The internal resistance of each cell is `0.5Omega`. What are the values of m and n, if the total number of cells are 20?A. `m=2, n=10`B. m=4, n=5C. m=5, n=4D. n=2, m=10 |
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Answer» Correct Answer - A Total number of cells `(m+n)=20` For maximum current, R = nr/m ….(i) `rArr " " 2.5=n xx0.5//m` or n = 5 m From Eq. (i), `m xx 5m = 20` , or `m^(2)=4` `rArr m = 2`, therefore `n = 5xx2=10` |
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| 907. |
A wire has a resistance of 12 ohm . It is bent in the form of equilateral triangle. The effective resistance between any two corners of the triangle isA. 9 ohmsB. 12 ohmsC. 6 ohmsD. `8//3` ohms |
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Answer» Correct Answer - D |
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| 908. |
A series combination of two resistors `1 Omega` each is connected to a 12 V battery of internal resistance `0.4 Omega`. The current flowing through it will beA. `3.5A`B. `5A`C. `6A`D. `10A` |
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Answer» Correct Answer - B |
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| 909. |
What will be the value of current I in the circuit shown ? A. 0.67 AB. 1AC. 0.32 AD. None of these |
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Answer» Correct Answer - A Applying `KVL, V_(A)-V_(D)=-6i-5i+10-4i` Here, `V_(A)-V_(D)=0` Since, points A and D are centred. `-6i+5i+10-4i=0 rArr 15i=10` `rArr " " i=(10)/(15)=0.67 A` |
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| 910. |
The current in the given circuit is A. `0.1A`B. `0.2A`C. `0.3A`D. `0.4A` |
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Answer» Correct Answer - A |
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| 911. |
A series combination of two resistors `1 Omega` each is connected to a 12 V battery of internal resistance `0.4 Omega`. The current flowing through it will beA. 3.5AB. 5AC. 6AD. 10A |
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Answer» Correct Answer - B Here, both the external resistance are connected in series combination of battery. Hence, total external resistance `= 1+1=2 Omega` Hence, the toal resistance = external resistance + internal resistance `= 2+0.4=2.4 Omega` So, current flowing is `l=(V)/(R )=(12)/(2.4)=5 A` |
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| 912. |
The e.m.f. of a cell is aA. unit vectorB. zero vectorC. scalar quantityD. vector quantity |
| Answer» Correct Answer - C | |
| 913. |
The energy spent by the cell in circulating unit charge once through the complete circuit isA. e.m.f of cellB. terminal potential difference of cellC. current capacityD. force |
| Answer» Correct Answer - A | |
| 914. |
Which of the follwing characteristies of electrons determines the current in a conductor?A. Drift velocity alongB. Thermal velocity aloneC. Both drift velocity and tehrmal velocityD. Neither drift nor thermal velocity. |
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Answer» Correct Answer - A The relationship between current and drift speed is given by `I=n e" "Av_(d)` Here, I is the current and `v_(d)` is the drift velocity So, `I propv_(d)` Thus, only drift velocity determines the current in a conductor. |
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| 915. |
The internal resistance of a cell of e.m.f. 12 V is `5 xx 10^(-2) Omega`. It is connected across an unknown resistance. Voltage across the cell, when a current of 60 A is drawn from it, isA. 15VB. 12VC. 9VD. 6V |
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Answer» Correct Answer - C |
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| 916. |
In the given circuit the current l is A. `0.4A`B. `-0.4 A`C. `0.8A`D. `-0.8A` |
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Answer» Correct Answer - B |
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| 917. |
The voltmeter in figure has a resistance of `200 Omega`. The reading of voltmeter is A. 2 VB. 1 VC. 1.5 VD. 3 V |
| Answer» Correct Answer - C | |
| 918. |
A metel rod of the length 10cm and a rectangular cross-section of 1 cm xx `1//2` cm is connected to a battery across opposite faces. The resistance will beA. maximum when the battery is connected across `"1 cm"xx(1//2)` cm facesB. maximum when the battery is connected across `"10 cm"xx(1)` cm facesC. maximum when the battery is connected across `"1= cm"xx(1//2)` cm facesD. same irrepective of the three faces |
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Answer» Correct Answer - A |
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| 919. |
A metel rod of the length 10cm and a rectangular cross-section of 1 cm xx `1//2` cm is connected to a battery across opposite faces. The resistance will beA. maximum when the battery is connected across `1cmxx(1)/(2)cm` facesB. maximum when the battery is connected across `10cmxx1cm` facesC. maximum when the battery is connected across `10cmxx(1)/2 cm` faces.D. Same irrespective of the three faces. |
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Answer» Correct Answer - A The resistance of wire is given by `R=rho(l)/(A)` For greater value of R, l must be higher and A should be lower and it is possible only when the battery is connected across `1cmxx((1)/(2))cm` (area of cross-section A). |
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| 920. |
A 6 V battery is connected to the terminals of a 3 m long wire of uniform thickness and resistance of `100 Omega`. The difference of potential between two points on the wire separated by a distance of 50 cm will beA. 2 VB. 3 VC. 1 VD. 15 V |
| Answer» Correct Answer - C | |
| 921. |
A metel rod of the length 10cm and a rectangular cross-section of 1 cm xx `1//2` cm is connected to a battery across opposite faces. The resistance will beA. maximum when the battery is connected across `1cm(1)/(2)cm` facesB. maximum when the battery is connected across `10cmxx1cm` facesC. maximum when the battery is connected across `10cmxx(1)/(2)cm` facesD. same irrespective of the three faces |
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Answer» The resistance of wire is given by `R=rho(l)/(A)` for greater value of `R`, l must be higher and A should be lower and it is possible only when the battery is connected across `1cmxx((1)/(2))cm` (area of cross-section A). |
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| 922. |
A 2 V battery, a `990Omega` resistor and a potentiometer of 2 m length, all are connected in series of the resistance of potentiometer wire is `10Omega`, then the potential gradient of the potentiometer wire isA. `0.05Vm^(-1)`B. `0.5Vm^(-1)`C. `0.01Vm^(-1)`D. `0.1Vm^(-1)` |
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Answer» Correct Answer - C |
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| 923. |
A wire of 50 cm long, `1mm^(2)` in cross-section carries a current of 4 A, when connected to a 2 V battery, the resistivity of wire isA. `2xx10^(-7)Omega-m`B. `5xx10^(-7)Omega-m`C. `4xx10^(-6)Omega-m`D. `1xx10^(-6)Omega-m` |
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Answer» Correct Answer - D |
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| 924. |
The resistance of a semicircle shown in fig. Between its two end faces is (Given that radial thickness `=3cm`, axial thickness `=4cm`, inner radius `=6cm` and resistivity `=4xx10^(-6)Omegacm`)A. `24.15xx10^(-6)Omega`B. `7.85xx10^(-7)Omega`C. `7.85xx10^(-6)Omega`D. `7.85xx10^(-5)Omega` |
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Answer» Correct Answer - C Here, `A=4cmxx3cm=12cm^(2)` `l=pir=pi(6+(3)/(2))=pixx7.5cm` `R=(rhol)/(A)=(4xx10^(-6)xxpixx7.5)/(12)` `=7.85xx10^(-6)ohm`. |
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| 925. |
The number density of free electrons in a copper conductor is estimated at `8.5 xx 10^(28) m^(-3)`. How long does an electron take to drift from one end of a wire 3.0 m long to its other end? The area of cross-section of the wire is `2.0 xx 10^(-6)m^(2)` and it is carrying a current of 3.0A. |
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Answer» Number density of free electrons in a copper conductor, `n = 8.5 xx 10^(28) m^(-3)` Length of the copper wire, `l = 3.0` m Area of cross-section of the wire, `A = 2.0 xx 10^(-6) m^(2)` Current carried by the wire, `I = 3.0A`, which is given by the relation, `I = nAeV_(d)` where, e = Electric charge `= 1.6 xx 10^(-19)C` `V_(d) = "Drift velocity" = ("Length of the wire" (l))/("Time taken to cover" (t))` `I = nAe(l)/(t)` `t = (nAel)/(I)` `= (3 xx 8.5 xx 10^(28) xx 2xx 10^(-6) xx 1.6 xx 10^(-19))/(3.0)` `= 2.7 xx 10^(2)s` Therefore, the time taken by an electron to drift from one end of the wire to the other is `2.7 xx 10^(4)s`. |
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| 926. |
During the melting of a slab of ice at 273K at atmospheric pressure,A. positive work is done by the ice water system on the atmosphereB. positive work is done on the ice water system by the atmosphereC. the internal energy of the ice water system increasesD. the internal energy of the ice water system decreases |
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Answer» Correct Answer - B::C |
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| 927. |
Two rods of different materials are placed between massive walls as shown in figure. The cross section of the rods is A, their moduil of elastricity are `E_(1)` and `E_(2)` respectively. If rods are heated by t degrees, then (coefficients of liner expansion of material of rods are `alpha_(1)` and `alpha_(2)` respectively) A. the strain produced in both rods is equalB. the stress produced in both the rods is equalC. the force exerted by one rod on the other is `(alpha_(1)l_(1)+alpha_(2)l_(2))/((l_(1))/(E_(1))+(l_(2))/(E_(2)))At`D. the force exerted by one rod on the other is `((E_(1)-E_(2))^(2)A)/(E_(1)+E_(2))` |
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Answer» Correct Answer - B::C |
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| 928. |
Sarita a house wife had been using in his house an inverter and a lead acit battery set for the last two year ,soddenly she felt problem of low voltage and less back up from inverter instead of calling an electrician , she tried to set it right .On checking notes that the level of electrolyte was less than required in the battery to ralse the electroles to required level After doing on she notes that above that battery was permanely damamged (i) What wrong was done by sarita ? (ii) What was the right way for sarita to gas rid of the problem ? (iii) What do you learn from the above study? |
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Answer» (i) sarita used acit insead of distlled water in the bettery to rise the level of electrolyte (ii) sarita should have sells an electrician who is execpet in deling with the inverter and battery (iii) A little knowladge is a dangererous thing Therefor one should handle an appliance or apparaton when one has complete knowledge and information about it |
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| 929. |
Two metal rods X and Y having equal cross-sectional areas are joined in series. One end of which is heated. After some time, the temperature gradient along each rod is foound to be uniform, but greater in X than that in Y. Which of the following can be inferredA. both the rods may be of different lengthsB. The heat current is the same in both the rodsC. Both the rods are of equal lengthsD. X is better conductor of heat than Y |
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Answer» Correct Answer - A::B |
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| 930. |
When resistres of resistyences `R_(1)R_(2) and R_(3)` are connected in series , then the resistance`R_(1)` is given by `R_(1) = R_(1) + R_(2) +R_(3)` In this arrengement the current through each resister is same hut potential difference across then is difference When resitorce of resistance `R_(1)R_(2) and R_(3)` are connected in particle the effective resistance `R_(p)` is given by `(1)/(R_(p)) = (1)/(R_(1)) + (1)/(R_(2)) + (1)/(R_(3))` In this arrangement , the potential difference across each resistance is but current through then is difference Read the above passage and answer the following question : (i) Why does the effective resistance increase in series ? (ii) Why does the effective resistance decrease in parallel ? (iii) What basic value are displayed by the above study ? |
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Answer» (i)When resistance are connected in series , there is only one channel for the flow currect .Due to it , the effective puth length (l) for current increase .As resistance `R prop 1` hence effective resistance increase (ii) When resistance are connected in parallel , there are difference channel for the flow of current due to it the effective area of cross- series `(A)` of the parallel of resistance increase As `R prop 1//A` so the effective resistance decrease. (iii) In day life , resistance corresponding and current corresponding to the output from the source When resistance are is series oppsition increase and output reduces When resistance are ibn parallel each is in direct with source of current the opposition decrease and the output increase .Thus to achives best resites every inember must be in direct contact with the source//family head. |
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| 931. |
Define resistively or specific resistance. |
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Answer» Resistively or specific resistance `(rho)` : The resistance of a conductor of unit length and unit area of cross-section is called resistivity. If `l = 1, A =1 implies rho = (R xx 1)/(1) = rho implies R` |
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| 932. |
The resistance of a bulb filmanet is `100Omega` at a temperature of `100^@C`. If its temperature coefficient of resistance be 0.005 per `.^@C`, its resistance will become `200 Omega` at a temperature ofA. `300^(@)C`B. `400^(@)C`C. `500^(@)C`D. `200^(@)C` |
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Answer» Correct Answer - B `alpha=(R_(2)-R_(1))/(R_(1)t_(2)-R_(2)t_(1))` |
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| 933. |
When two resistance are connected in parallel then the equivalent resistance is `(6)/(5)Omega` When one of the resistance is removed then the effective resistance is `2Omega`. The resistance of the wire removed will beA. 3 ohmB. 2 ohmC. `(3)/(5)ohm`D. `(6)/(5)ohm` |
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Answer» Correct Answer - A `(R_(1)R_(2))/(R_(1)+R_(2))=(6)/(5)`. If `R_(2)` is removed `R_(1)=2Omega` `(2R_(2))/(2+R_(2))=(6)/(5)implies5R_(2)=6+3R_(2)impliesR_(2)=3Omega` |
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| 934. |
When we switch on the lights one after the other, what is the effect on the resistance of the electric circuit of the house ? On the current flowing in the main circuit? |
| Answer» In a house, all lights are in parallel circuits, to a fixed supply voltage 220V. When we switch on lights one after the other, the effective resistance of the circuit goes on decreasing. As a result of it, the main current goes on increasing. | |
| 935. |
The resistively of a condu is given by the expression : `p = RA//l` where `R` is the independent of dimension of conductor it deped on the meters of material and temperature of condections Read the show paragraph and answer the following question: (i) For whichmeterial is the resistivity (i) zero (ii) infinite ? (ii) Find the resistent of a bellow cylindrical of the meterial of cylinderical pipe is `2 xx 10^(-3) Omega m` (iii) How is the knowinledge of resistance metel in over dally life ? |
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Answer» The resistively is zero for toper conbinations like at critical temperature `4.2K` motion at critical temperature `9.2k` and the resistance is inifnite for a perfect insilner like dry wood and hard glass (i) Here`I = 1.0cm,r_(1)= 0.10m, r_(2)= 0.20 m,rho= 2xxx10^(-6)Omega m` `R=(rhol)/(pi(r_(2)^(2)-r_(1)^(2)))=((2xx10^(-8))xx1)/((22//7)[(0.2)^(2)-(0.1)^(2)])=2.1 xx10^(-7) Omega` (iii) The knowladge of respectively of difference meterial helps as in selecting satable material for differece perposs for example a in making a tranedrelasence cell magain or constant wire is used as in resistanceis very lange .The length required for a given resistance would be small b in making the heater cell inclinedd wire is used as in resistance and inclined are high c copper wire are used as connecting wires to electrical experiment of copper is very low |
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| 936. |
`G_(1), G_(2), G_(3)` are the conductances of three conductors. What will be their equivalent conductance when they are connected, (i) in series (ii) in parallel. |
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Answer» Conductance is reciprocal of resistance, so `R_(1)=1/G_(1), R_(2)1/G_(2), R_(3) = 1/G_(3)` When conductors are in series, then `R= R_(1) +R_(2)+R_(3)` `:. 1/G = 1/G_(1) +1/G_(2) +1/G_(3)= (G_(2)G_(3) +G_(1)G_(3) +G_(1)G_(2))/(G_(1)G_(2)G_(3))` or `G = (G_(1)G_(2)G_(3))/(G_(2)G_(3) +G_(1)G_(3) +G_(1)G_(2))` When conductors are in parallel, then `1/R = 1/R_(1) +1/R_(2) +1/R_(3) :. G = G_(1) ++ G_(2) + G_(3)` |
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| 937. |
The combined resistance of two conductors in series is `1Omega`. If the conductance of one conductor is 1.1 siemen, the conductance of the other conductor is siemen isA. 10B. 11C. 1D. 1.1 |
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Answer» Correct Answer - B `R_(1)+R_(2)=1ohm` `(1)/(R_(1))=1.1implies R_(1)=(10)/(11)` `R_(2)=1-R_(1)therefore(1)/(R_(2))=(1)/(1-R_(1))` |
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| 938. |
Two rods of copper and aluminium of each equal length 20 cm and equal cross-sectional area `2 mm^(2)`. They are joined (i) in series and (ii) in parallel as shown in figure. Find the resistance of the combination in each case. Resistivity of copper `=1.7 xx10^(-8) Omega m` and resistivity of aluminium `= 2.6 xx 10^(-8)Omega m`. |
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Answer» For copper rod, `l=20 cm=0.20 m`, `A=2 mm^(2)=2xx10^(-6) m^(2), rho =1.7 xx10^(-8)Omega m` `R_(1) = rho l/A=((1.7 xx10^(-8)) xx 0.20)/(2xx10^(-6))= 1.7 xx10^(-3)Omega` For aluminium rod, l =20 cm =0.20 m, `A= 2mm^(2) = 2xx10^(-6) m^(2), rho= 2.6 xx 10^(-8)Omega m` `R_(2)=((2.6 xx 10^(-8))xx0.20)/(2xx10^(-6)) = 2.6 xx 10^(-3) Omega` (i) When two rods are joined in series, their equivalent resistance, `R = R_(1) +R_(2) =1.7 xx 10^(-3) +2.6 xx10^(-3)` `~~ 4.3 xx 10^(-3)Omega` (ii) When rods are in parallel, the equicvalent resistance is `R =(R_(1)R_(2))/(R_(1)+R_(2))=((1.7 xx 10^(-3)) xx(2.6 xx 10^(-3)))/((1.7 xx 10^(-3)) + (2.6 xx 10^(-3)))` `=(1.7 xx 2.6 xx 10^(-3))/4.3 =1.028 xx 10^(-3)Omega` `=1.028 mOmega` |
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| 939. |
graph of an ideal gas is as shown in figure. Heat is supplied to the gas in process (s).A. da, ab and bcB. da and abC. da onlyD. ab and bc |
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Answer» Correct Answer - B |
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| 940. |
graph of an ideal gas is as shown in figure. Work done by the gas in complete cyclic process about isA. zeroB. positiveC. negativeD. Data is insufficient |
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Answer» Correct Answer - C |
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| 941. |
Why is the meter bridge suitable for resistance of moderate values only ? |
| Answer» For measuring high resistance, the resistances of all other arms of the bridge should also be high in ordere to ensure the sensitivity of the bridge. But this will reduce the current through the galvanometer. As a result of it, the galvanometer becomes insensitive. | |
| 942. |
Potentiometer in so named becomes it measures…….. |
| Answer» Correct Answer - potential difference | |
| 943. |
The material of wire of potentiometer isA. CopperB. SteelC. ManganinD. Aluminium |
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Answer» Correct Answer - C |
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| 944. |
Why is a potentiometer named as potentiometer ? |
| Answer» It is so named because it is used to measure potential difference. | |
| 945. |
Why should the potentiometer wire be of uniform cross-section and composition ? |
| Answer» The potentiometer wire should be of uniform cross-section and composition so that there is same resistance per unit length throughout. Only then, potential difference will be proportional to length of the potentiometer wire, which is the requirement for the principal of potentiometer. | |
| 946. |
Of which material is a potentiometer wire normally made and why ? |
| Answer» Normally, the potentiometer wire is made of an alloy such as nichrome or manganin. Because those alloys have high resistivity and low temperature coefficient of resistance. | |
| 947. |
Can we use copper wire as potentiometer wire ? Explain. |
| Answer» Copper wir cannot be used as a potentiometer wire because resistivity of copper is low. Due to it, there will not be suitable potential drop across the ends of the potentiometer wire. Also the temperature coefficient of resistance of copper is large. | |
| 948. |
Explain, why should the current be not passed through potentiometer wire for long time ? |
| Answer» If the current in potentiometer wire is passed for long time, the potentiometer wire will get heated. Its resistance will change. Due to it, the potential gradient per unit length of the wire will also change. | |
| 949. |
The emf of the driving cell used in the main circuit of the potentiometer should be more than the potential differnce to be measured. Why? |
| Answer» If it is not so, then the balance point will not be obtained on the potentiometer wire. | |
| 950. |
Some times balance point may not be obtained on the potentiometer wire. Why? |
| Answer» It is possible only if the fall of potential across the potentiometer wire is less than the potential difference to be balanced by the potentiometer wire. | |