Current Electricity NEET

NEET-2022

Question 1. The reciprocal of resistance is :

(a) conductance
(b) reactance
(c) mobility
(d) conductivity

Answer (a)

Question 2. The distance between the two plates of a parallel plate capacitor is doubled and the area of each plate is halved. If `C` is its initial capacitance, its final capacitance is equal to

(a) `C/4`

(b) `2C`

(c) `C/2`

(d) `4C`

Answer (a)

Question 3. A cell of emf `4 V` and internal resistance `0.5\Omega` is connected to a `7.5\Omega` external resistance. The terminal potential difference of the cell is

(a) `0.375V`
(b) `3.75V`
(c) `4.25V`
(d) `4V`

Answer (b)

Question 4. The equivalent resistance of the infinite network given below is :

(a) `(1+\sqrt{5})\Omega`
(b) `2\Omega`
(c) `(1+\sqrt{2})\Omega`
(d) `(1+\sqrt{3})\Omega`

Answer (d)

Question 5. The effective capacitances of two capacitors are `3\mu F` and `16\muF`, when they are connected in series and parallel respectively. The capacitance of two capacitors are :

(a) `1.2\muF,1.8\muF`
(b) `10\muF,6\muF`
(c) `8\muF,8\muF`
(d) `12\muF,4\muF`

Answer (d)

Question 6. The sliding contact C is at one-fourth of the length of the potentiometer wire (AB) from A as shown in the circuit diagram. If the resistance of the wire AB is `R_0`, then the potential drop `(V)` across the resistor `R` is

(a) `{2V_0R}/{2R_0+3R}`

(b) `{4V_0R}/{3R_0+16R}`

(c) `{4V_0R}/{3R_0+R}`

(d) `{2V_0R}/{4R_0+3R}`

Answer (b)

Question 7. Two resistors of resistance, `100\Omega` and `200 \Omega` are connected in parallel in an electrical circuit. The ratio of the thermal energy developed in `100\Omega`

to that in `200 \Omega`

in a given time is

(a) `1:2`
(b) `2:1`
(c) `1:4`
(d) `4:1`

Answer (b)

Question 8. A copper wire of length `10 m` and radius `({10^-2}/sqrt{\pi}) m` has electrical resistance of `10 \Omega`. The current density in the wire for an electric field strength of `10 (V/m)` is

(a) `10^4A/m^2`

(b) `10^6A/m^2`

(c) `10^-5A/m^2`

(d) `10^5A/m^2`

Answer (d)

Question 9. A capacitor of capacitance `C = 900 pF` is charged fully by `100 V` battery `B` as shown in figure (a). Then it is disconnected from the battery and connected to another uncharged capacitor of capacitance `C = 900 pF` as shown in figure (b). The electrostatic energy stored by the system (b) is

(a) `4.5\times10^-6J`
(b) `3.25\times10^-6J`
(c) `2.25\times10^-6J`
(d) `1.5\times10^-6J`

Answer (c)

Question 10. A wheatstone bridge is used to determine the value of unknown resistance X by adjusting the variable resistance Y as shown in the figure. For the most precise measurement of X, the resistance P and Q

(a) Should be approximately equal to 2X

(b) Should be approximately equal and are small

(d) Do not play any significant role

Answer (b)

NEET-2021

Question 11. A parallel plate capacitor has a uniform electric field `vec{E}` in the space between the plates. If the distance between the plates is 'd' and the area of each plate is 'A', the energy stored in the capacitor is : `(\varepsilon_0 =` permittivity of free space)

(a) `{E^2Ad}/{\varepsilon_0}`

(b) `1/2\varepsilon_0E^2`

(c) `\varepsilon_0EAd`

(d) `1/2\varepsilon_0E^2Ad`

Answer (d)

Question 12. A capacitor of capacitance `'C'`, is connected across an ac source of voltage `V`, given by `V = V_0sin\omegat` The displacement current between the plates of the capacitor, would then be given by :

(a) `I_d=V_0\omegaCsin\omegat`

(b) `I_d=V_0\omegaCcos\omegat`

(c) `I_d=V_0/{\omegaC}cos\omegat`

(d) `I_d=V_0/{\omegaC}sin\omegat`

Answer (b)

Question 13. In a potentiometer circuit a cell of EMF `1.5 V `gives balance point at 36 cm length of wire. If another cell of EMF `2.5 V` replaces the first cell, then at what length of the wire, the balance point occurs?

(a) `62cm`
(b) `60cm`
(c) `21.6cm`
(d) `64cm`

Answer (b)

Question 14. The effective resistance of a parallel connection that consists of four wires of equal length, equal area of cross-section and same material is `0.25\Omega`. What will be the effective resistance if they are connected in series?

(a) `4\Omega`
(b) `0.25\Omega`
(c) `0.5\Omega`
(d) `1\Omega`

Answer (a)

Question 15. The equivalent capacitance of the combination shown in the figure is :

(a) `{3C}/2`

(b) `3C`

(c) `2C`

(d) `C/2`

Answer (c)

Question 16. Three resistors having resistances `r_1, r_2` and `r_3` are connected as shown in the given circuit. The ratio `i_3/i_1` of currents in terms of resistances used in the circuit is :

(a) `r_2/{r_1+r_3}`

(b) `r_1/{r_2+r_3}`

(c) `r_2/{r_2+r_3}`

(d) `r_1/{r_1+r_2}`

Answer (c)

NEET-2020

Question 17. A resistance wire connected in the left gap of a metre bridge balances a `10 \Omega` resistance in the right gap at a point which divides the bridge wire in the ratio `3:2`. If the length of the resistance wire is `1.5 m`, then the length of `1\Omega` of the resistance wire is :

(a) `1.0\times10^-1m`
(b) `1.5\times10^-1m`
(c) `1.5\times10^-2m`
(d) `1.0\times10^-2m`

Answer (a)

Question 18. The color code of a resistance is given below :

The values of resistance and tolerance, respectively, are

(a) `47k\Omega, 10%`
(b) `4.7k\Omega, 5%`
(c) `470\Omega, 5%`
(d) `470k\Omega, 5%`

Answer (c)

Question 19. A charged particle having drift velocity `7.5\times10^-4 ms^-1` in an electric field of `3\times10^-10 Vm^-1` has a mobility in `m^2 V^-1s^-1` of :

(a) `2.5\tomes10^6`
(b) `2.5\tomes10^-6`
(c) `2.25\tomes10^-15`
(d) `2.25\tomes10^15`

Answer (a)

Question 20. Which of the following graph represents the variation of resistivity `(\rho)` with temperature (T) for copper?

(a)

(b)

(c)

(d)

Answer (b)

Question 21. The solids which have the negative temperature coefficient of resistance are :

(a) insulators only

(b) semiconductors only

(d) metals

Answer (c)

NEET-2019

Question 22. Six similar bulbs are connected as shown in the figure with a DC source of emf E, and zero internal resistance.

The ratio of power consumption by the bulbs when (i) all are glowing and (ii) in the situation when two from section A and one from section B are glowing, will be :

(a) `4:9`
(b) `9:4`
(c) `1:2`
(d) `2:1`

Answer (b)

Question 23. In the circuits shown below, the readings of voltmeters and the ammeters will be :

(a) `V_1=V_2 &i_1=i_2`

(b) `V_>1V_2 &i_1>i_2`
(b) `V_1>V_2 &i_1=i_2`
(c) `V_1=V_2 &i_1>i_2`

Answer (a)

Question 24. Which of the following acts as a circuit protection device?

(a) inductor
(b) conductor
(c) switch
(d) fuse

Answer (d)

NEET-2018

Question 25. A battery consists of a variable number `n` of identical cells (having internal resistance r each) which are connected in series. The terminals of the battery are short-circuited and the current `I` is measured. Which of the graphs shows the correct relationship between `I` and `n`?

(a)

(b)

(c)

(d)

Answer (c)

Question 26. A carbon resistor of `(47\pm 4.7) k\Omega` is to be marked with rings of different colours for its identification. The colour code sequence will be

(a) Violet-Yellow-Orange-Silver
(b) Yellow-Violet-Orange-Silver
(c) Yellow-GRreen-Violet-Gold
(d) Green-Orange-Violet-Gold

Answer (b)

Question 27. A set of n equal resistors, of value `R` each, are connected in series to a battery of emf E and internal resistance `R`. The current drawn is `I`. Now, the n resistors are connected in parallel to the same battery. Then the current drawn from battery becomes `10I`. The value of n is

(a) `10`
(b) `11`
(c) `20`
(d) `9`

Answer (a)

NEET-2017

Question 28. The resistance of a wire is `'R'` ohm. If it is melted and stretched to 'n' times its original length. its new resistance will be

(a) `R/n`
(b) `n^2R`
(c) `R/n^2`
(d) `nR`

Answer (b)

Question 29. 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

(d) cells

Answer (b)

NEET-2016

Question 30. The potential difference `(V_A- V_B)` between the points A and B in the given figure is

(a) `-3V`
(b) `+3V`
(c) `+6V`
(d) `+9V`

Answer (d)

Question 32. A filament bulb `(500 W, 100 V)` is to be used in a `230 V` main supply. When a resistance R is connected in series, it works perfectly and the bulb consumes `500 W.` The value of `R` is

(a) `230\Omega`
(b) `46\Omega`
(c) `26\Omega`
(d) `13\Omega`

Answer (c)

Question 33. A potentiometer wire is `100 cm` long and a constant potential difference is maintained across it. Two cells are connected in series first to support one another and then in opposite direction. The balance points are obtained at `50 cm` and `10 cm` from the positive end of the wire in the two cases. The ratio of emf's is

(a) `3:4`
(b) `3:2`
(c) `5:1`
(d) `5:4`

Answer (b)

Question 34. The charge flowing through a resistance `R` varies with time `t` is `Q = at- bt^2`, where `a` and `b` are positive constants. The total heat produced in `R` is

(a) `{a^3R}/{2b}`

(b) `{a^3R}/{b}`

(c) `{a^3R}/{6b}`

(d) `{a^3R}/{3b}`

Answer (c)

NEET-2015

Question 35. Two metal wires of identical dimensions are connected in series. If `\sigma_1` and `\sigma_2` are the conductivity of the combination is

(a) `{\sigma_1+\sigma_2}/{\sigma_1\sigma_2}`

(b) `{\sigma_1\sigma_2}/{\sigma_1+\sigma_2}`

(c) `{2\sigma_1\sigma_2}/{\sigma_1+\sigma_2}`

(d) `{\sigma_1+\sigma_2}/{2\sigma_1\sigma_2}`

Answer (c)

Question 36. A circuit contains an ammeter, a battery of `30 V` and a resistance `40.8` ohm all connected in series. If the ammeter has a coil of resistance `480` ohm and a shunt of `20` ohm, the reading in the ammeter will be

(a) `2A`
(b) `1A`
(c) `0.5A`
(d) `0.25A`

Answer (c)

Question 37. A potentiometer wire of length `L` and a resistance r are connected in series with a battery of e.m.f. `E_0` and a resistance `r_1`. An unknown e.m.f. `E` is balanced at a length `l` of the potentiometer wire. The e.m.f. `E` will be given by

(a) `{E_0l}/L`

(b) `{LE_0r}/{(r+r_1)l}`

(c) `{LE_0r}/{r_1l}`

(d) `{E_0r}/{(r+r_1)}.l/L`

Answer (d)

Question 38. Across a metallic conductor of non-uniform cross section a constant potential difference is applied. The quantity which remains constant along the conductor is

(a) drift velocity
(b) electric field
(c) current density
(d) current

Answer (d)

Question 39. A, B and C are voltmeters of resistance `R, 1.5 R` and `3R` respectively as shown in the figure. When some potential difference is applied between `X` and `Y`, the voltmeter readings are `V_A, V_B` and `V_C` respectively, Then

(a) `V_A=V_B\neqV_C`
(b) `V_A\neqV_B\neqV_C`
(c) `V_A=V_B=V_C`
(d) `V_A\neqV_B=V_C`

Answer (c)

Question 40. A potentiometer wire has length `4 m` and resistance `8\Omega` . The resistance that must be connected in series with the wire and an accumulator of e.m.f. `2 V`, so as to get a potential gradient `1 mV` per `cm` on the wire is

(a) `44\Omega`
(b) `48\Omega`
(c) `32\Omega`
(d) `40\Omega`

Answer (c)

NEET-2014

Question 41. The resistances in the two arms of the meter bridge are `5\Omega` and `R\Omega` respectively. When the resistance `R` is shunted with an equal resistance, the new balance point is at `1.6l_1`. The resistance `R` is

(a) `10\Omega`
(b) `15\Omega`
(c) `20\Omega`
(d) `25\Omega`

Answer (b)

Question 42. A potentiometer circuit has been set up for finding the internal resistance of a given cell. The main battery, used across the potentiometer wire, has an emf of `2.0 V` and a negligible internal resistance. The potentiometer wire itself is `4 m` long. When the resistance `R`, connected across the given cell, has values of (i) infinity, (ii) `9.5\Omega` the balancing lengths on the potentiometer wire are found to be `3 m` and `2.85 m`, respectively. The value of internal resistance of the cell is

(a) `0.25\Omega`
(b) `0.95\Omega`
(c) `0.5\Omega`
(d) `0.75\Omega`

Answer (c)

Question 43. Two cities are `150 km` apart. Electric power is sent from one city to another city through copper wires. The fall of potential per km is `8` volt and the average resistance per `km` is `0.5\Omega`. The power loss in the wire is

(a) `19.2W`
(b) `19.2KW`
(c) `19.2J`
(d) `12.2KW`

Answer (b)

NEET-2013

Question 44. Two rods are joined end to end, as shown. Both have a cross-sectional area of `0.01 cm^2`. Each is `1` meter long. One rod is of copper with a resistivity of `1.7\times10^-6` ohm-centimeter, the other is of iron with a resistivity of `10^-5` ohm-centimeter.

How much voltage is required to produce a current of 1 ampere in the rods?

(a) `0.00145V`
(b) `0.0145V`
(c) `1.7\times10^-6V`
(d) `0.117V`

Answer (d)

Question 45. A `12 cm` wire is given a shape of a right angled triangle ABC having sides `3 cm, 4 cm` and `5 cm` as shown in the figure. The resistance between two ends (AB, BC, CA) of the respective sides are measuread one by one ratio

(a) `9:16:25`
(b) `27:32:35`
(c) `21:24:25`
(d) `3:4:5`

Answer (b)

Question 46. Ten identical cells connected in series are needed to heat a wire of length one meter and radius `'r'` by `10^oC` in time `'t'`. How many cells will be required to heat the wire of length two meter of the same radius by the same temperature in time `'t'` ?

(a) `20`
(b) `30`
(c) `40`
(d) `10`

Answer (a)

Question 47. The resistances of the four arms P, Q, R and S in a Wheatstone's bridge are `10` ohm, `30` ohm, `30` ohm and `90` ohm, respectively. The e.m.f. and internal resistance of the cell are 7 volt and 5 ohm respectively. If the galvanometer resistance is `50` ohm, the current drawn from the celll will be

(a) `0.1A`
(b) `2.0A`
(c) `1.0A`
(d) `0.2A`

Answer (d)

Question 48. The internal resistance of a `2.1 V` cell which gives a current of `0.2 A` through a resistance of `10 \Omega` is

(a) `0.8\Omega`
(b) `1.0\Omega`
(c) `0.2\Omega`
(d) `0.5\Omega`

Answer (d)

Question 49. A wire of resistance `4\Omega` is stretched to twice its original length. The resistance of stretched wire would be

(a) `8\Omega`
(b) `16\Omega`
(c) `2\Omega`
(d) `4\Omega`

Answer (b)

NEET-2012

Question 50. A cell having an emf `\varepsilon` and internal resistance r is connected across a variable external resistance R. As the resistance R is increased, the plot of potential difference V across R is given by

(a)

(b)

(c)

(d)

Answer (b)

Question 51. The power dissipated in the circuit shown in the figure is `30` watts. The value of `R` is

(a) `20\Omega`
(b) `15\Omega`
(c) `10\Omega`
(d) `30\Omega`

Answer (c)

Question 52. In the circuit shown the cells A and B have negligible resistances. For `V_A = 12 V, R_1 = 500\Omega` and `R = 100\Omega` the galvanometer `(G)` shows no deflection. The value of `V_s` is

(a) `4V`
(b) `2V`
(c) `12V`
(d) `6V`

Answer (b)

Question 53. A ring is made of a wire having a resistance `R_0 = 12\Omega`. Find the points A and B, as shown in the figure, at which a current carrying conductor should be connected so that the resistance R of the sub circuit between these point is equal to `8/3\Omega`.

(a) `l_1/l_2=5/8`

(b) `l_1/l_2=1/3`

(c) `l_1/l_2=3/8`

(d) `l_1/l_2=1/2`

Answer (d)

Question 54. If voltage across a bulb rated `220` volt-`100` watt drops by `2.5%` of its rated value, the percentage of the rated value by which the power would decrease is

(a) `20%`
(b) `2.5%`
(c) `5%`
(d) `10%`

Answer (c)

NEET-2011

Question 55. In the circuit shown in the figure, if the potential at point A is taken to be zero, the potential at point B is

(a) `+1V`
(b) `-1V`
(c) `+2V`
(d) `-2V`

Answer (a)

Question 56. A thermocouple of negligible resistance produces an e.m.f. of `40 {µV}/{ºC}` in the linear range of temperature. A galvanometer of resistance `10` ohm whose sensitivity is `1 µA`/division, is employed with the thermocouple. The smallest value of temperature difference that can be detected by the system will be

(a) `1^oC`
(b)`0.5^oC`
(c)`0.1^oC`
(d)`0.25^oC`

Answer (d)

Question 57. A current of `2 A` flows through a `2\Omega` resistor when connected across a battery a `2\Omega` resistor when connected across a battery. The same battery supplies a current of `0.5 A` when connected across a `9\Omega` resistor. The internal resistance of the battery is

(a) `0.5\Omega`

(b) `1/3\Omega`

(c) `1/4\Omega`

(d) `1\Omega`

Answer (b)

Question 58. If power dissipated in the `9\Omega` resistor in the circuit shown is `36` watt, the potential difference across the `2\Omega` resistor is

(a) `4`Volt
(b) `8`Volt
(c) `10`Volt
(d) `2`Volt

Answer (c)

NEET-2010

Question 59. Consider the following two statements.

(A) Kirchoff's junction law follows from the conservation of charge.

(B) Kirchhoff's loop law follows from the conservation of energy.

Which of the following is correct?

(a) Both (A) and (B) are wrong

(b) (A) is correct and (B) is wrong

(d) Both (A) and (B) are correct

Answer (d)

Question 60. A potentiometer circuit is set up as shown. The potential gradient, across the potentiometer wire, is `k v/cm` and the ammeter, present in the circuit, reads `1.0 A` when two way key is switched off. The balance points, when the key between the terminals (i) `1` and `2` (ii) `1` and `3`, is plugged in, are found to be at length `l_1 cm` and `l_2 cm` respectively. The magnitudes, of the resistors `R` and `X`, in ohms, are then, equal, respectively, to

(a) `k(l_2-l_1)` and `kl_2`
(b) `kl_1` and `k(l_2-l_1)`
(c) `k(l_2-l_1)` and `kl_1`
(d) `kl_1` and `kl_2`

Answer (b)

NEET-2009

Question 61. See the electrical circuit shown in this figure. Which of the following equations is a correct equation for it ?

(a) `\varepsilon_2-i_2r_2-\varepsilon-i_1r_1=0`
(b) `-\varepsilon_2-(i_1+i_2)R+i_2r_2=0`
(c) `\varepsilon_1-(i_1+i_2)R+i_1r_1=0`
(d) `\varepsilon_1-(i_1+i_2)R-i_1r_1=0`

Answer (d)

Question 62. A wire of resistance `12` ohms per meter is bent to form a complete circle of radius `10cm`. The resistance between its two diametrically opposite points, A and B as shown in the figure is

(a) `3\Omega`
(b) `6\pi\Omega`
(c) `6\Omega`
(d) `0.6\pi\Omega`

Answer (d)

Question 63. The mean free path of electrons in a metal is `4\times 10^-8 m`. The electric field which can give on an average `2 eV` energy to an electron in the metal will be in units `V/m`

(a) `5\times10^-11`
(b) `8\times10^-11`
(c) `5\times10^7`
(d) `8\times10^7`

Answer (c)

Question 64. A student measures the terminal potential difference `(V)` of a cell (of emf `\varepsilon` and internal resistance r) as a function of the current `(I)` flowing through it. The slope, and intercept, of the graph between `V` and `I`, then respectively, equal

(a) `-r& \varepsilon`
(b) `r & -\varepsilon`
(c) `-\varepsilon & r`
(d) `\varepsilon & -r`

Answer (a)

NET-2008

Question 65.

In the circuit shown, the current through the `4\Omega` resistor is `1 amp` when the points P and M are connected to `a d.c`. voltage source. The potential difference betwen the points M and N is

(a) `0.5`volt
(b) `3.2`volt
(c) `1.5`volt
(d) `1.0`volt

Answer (b)

Question 66. A wire of a certain material is stretched slowly by ten percent. Its new resistance and specific resistance become respectively

(a) both remain the same
(b) `1.1` times, `1.1` times
(c) `1.2` times, `1.1` times
(d) `1.21` times, same

Answer (d)

Question 67. An electric kettle takes `4 A` current at `220 V`. How much time will it take to boil `1 kg` of water from temperature `20^oC` ? The temperature of boiling water is `100^oC`

(a) `12.6 min`
(b) `4.2 min`
(c) `6.3 min`
(d) `8.4 min`

Answer (c)

Question 68. A current of `3 amp`. flows through the `2 \Omega` resistor shown in the circuit. The power dissipated in the `5\Omega` resistor is

(a) `1 Watt`
(b) `5 Watt`
(c) `4 Watt`
(d) `2 Watt`

Answer (b)

Question 69. A cell can be balanced against `110 cm` and `100 cm` of potentiometer wire, respectively with and without being short-circuited through a resistance of `10 \Omega`. Its internal resistance is

(a) `2.0ohm`
(b) zero
(c) `1.0ohm`
(d) `0.5ohm`

Answer (c)

NEET-2007

Question 70. Three resistances, `P, Q, R` each of `2\Omega` and an unknown resistance `S` from the four arms of a Wheatstone bridge circuit. When a resistance of `6\Omega` is connected in parallel to S the bridge gets balanced. What is the value of `S`?

(a) `3\Omega`
(b)`6\Omega`
(c)`1\Omega`
(d)`2\Omega`

Answer (a)

Question 71. The total power dissipated in watt in the circuit shown here is

(a) `40`
(b) `54`
(c) `4`
(d) `16`

Answer (b)

NEET-2006

Question 72. In the circuit shown, if a conducting wire is connected between points A and B, the current in this wire will

(a) flow from B to A
(b) flow from A to B
(c) flow in the direction which will be decided by the value of be zero
(d) be zero

Answer (a)

Question 73. Kirchoff's first and second laws of electrical circuits are consequences of

(a) conservation of energy and electric charge respectively

(b) conservation of energy

(d) conservation of electric charge.

Answer (c)

Question 74. Two cells, having the same e.m.f. are connected in series through an external resistance R. Cells have internal resistances `r_1` and `r_2 (r_1 > r_2)` respectively. When the circuit is closed, the potential difference across the first cell is zero. The value of `R` is

(a) `r_1+r_2`

(b) `r_1-r_2`

(c) `{r_1+r_2}/2`

(d) `{r_1-r_2}/2`

Answer (b)

Question 75. Power dissipated across the `8\Omega` resistor in the circuit shown here is `2` watt. The power dissipated in watt units across the `3\Omega` resistor is

(a) `3.0`
(b) `2.0`
(c) `1.0`
(d) `0.5`

Answer (a)

NEET-2005

Question 76. Two batteries, one of emf `18` volts and internal resistance `2\Omega`

and the other of emf `12` volts and internal resistance `1\Omega`, are connected as shown. The voltmeter `V` will record a reading of

(a) `30` volt
(b) `18` volt
(c) `15` volt
(d) `14` volt

Answer (d)

Question 77. When a wire of uniform cross-section `a` length `l` and resistance `R` is bent into a complete circle. resistance between any two of diametrically opposite points will be

(a) `R/2`

(b) `4R`

(c) `R/8`

(d) `R/2`

Answer (a)

Question 78. For the network shown in the figure the value of the current `i` is

(a) `{9V}/{35}`

(b) `{18V}/{5}`

(c) `{5V}/{9}`

(d) `{5V}/{18}`

Answer (d)

Question 79. A `5`-ampere fuse wire can withstand a maximum power of `1` watt in the circuit. The resistance of the fuse wire is

(a) `0.04 ohm`
(b) `0.2 ohm`
(c) `5 ohm`
(d) `0.4 ohm`

Answer (a)

NEET-2004

Question 80. Five equal resistances each of resistances `R` are connected as shown in the figure. A battery of `V` volts is connected between A and B. The current flowing in AFCEB will be

(a) `{3V}/{R}`

(b) `{v}/{R}`

(c) `{V}/{2R}`

(d) `{2V}/{R}`

Answer (c)

Question 81. when three identical bulbs of `60` watt, `200` volt rating are connected in series to a `200` volt supply, the power drawn by them will be

(a) `60` watt
(b) `180` watt
(c) `10` watt
(d) `20` watt

Answer (d)

Question 82. The electric resistance of a certain wire of iron is R. If its length and radius are both doubled, then

(a) The resistance will be doubled and the specific resistance will be halved.

(b) The resistance will be halved and the specific resistance will remain unchanged.

(d) The resistance and the specific resistance, will both remain unchanged.

Answer (b)

Question 83. In India electricity is supplied for domestic use at `220 V`. It is supplied at `110 V` in USA. If the resistance of a `60 W` bulb for use in India is `R`, the resistance of a `60 W` bulb for use in USA will be

(a) `R`

(b) `2R`

(c) `R/4`

(d) `R/2`

Answer (c)

Question 84. Resistance n, each of r ohm, when connected in parallel give an equivalent resistance of `R ohm`. If these resistances were connected in series, the combination would have a resistance in ohms, equal to

(a) `n^2R`

(b) `R/n^2`

(c) `R/n`

(d) `nR`

Answer (a)

Question 85. A `6` volt battery is connected to the terminals of a three metre long wire of uniform thickness and resistance of `100 ohm`. The difference of potential between two points on the wire separated by a distance of `50 cm` will be

(a) `2` Volt
(b) `3` Volt
(c) `1` Volt
(d) `1.5` Volt

Answer (c)

NEET-2003

Question 86. Two `220` volt, `100` watt bulbs are connected first in series and then in parallel. Each time the combination is connected to a `220` volt a.c. supply line. The power drawn by the combination in each case respectively will be

(a) `50` watt, `100` watt
(b) `100` watt, `50` watt
(c) `200` watt, `150` watt
(d) `50` watt, `200` watt

Answer (d)

Question 87. Fuse wire is a wire of

(a) high resistance and high melting point

(b) high resistance and low melting point

(d) low resistance and high melting point

Answer (b)

Question 88. In a Wheatstone's bridge all the four arms have equal resistance `R`. If the resistance of the galvanometer arm is also `R`, the equivalent resistance of the combination as seen by the battery is

(a) `R/4`
(b) `R/2`
(c) `R`
(d) `2R`

Answer (c)

Question 89. An electric kettle has two heating coils. When one of the coils is connected to an a.c. source, the water in the kettle boils in `10` minutes. When the other coil is used the water boils in `40` minutes. If both the coils are connected in parallel, the time taken by the same quantity of water to boil will be

(a) `8 min`
(b) `4 min`
(c) `25 min`
(d) `15 min`

Answer (a)

NEET-2002

Question 90. For a cell terminal potential difference is `2.2V` when circuit is open and reduce to `1.8 V` when cell is connected to a resistance of `R = 5\Omega`. Determine internal resistance of cell `(r)`

(a) `{10}/9\Omega`
(b) `9/{10}\Omega`
(c) `{11}/9\Omega`
(d) `5/9\Omega`

Answer (a)

Question 91. Specific resistance of a conductor increases with

(a) increase in temperature

(b) increase in cross-section area

(d) decrease in cross secton area.

Answer (a)

Question 92. The resistance of each arm of the Wheatstone's bridge is `10 ohm`. A resistance of `10 ohm` is connected in series with a galvanometer then the equivalent resistance across the battery will be

(a) `10 ohm`
(b) `15 ohm`
(c) `20 ohm`
(d) `40 ohm`

Answer (a)

Question 93. Copper and silicon is cooled from `300 K` to `60 K` , the specific resistance

(a) decrease in copper but increase in silicon

(b) increase in copper but decrease in silicon

(d) decrease in both

Answer (a)

Question 94. If specific resistance of a potentiometer wire is `10^-7 \Omega m` and current flow through it is `0.1 amp`., cross-sectional area of wire is `10^-6 m^2` then potential gradient will be

(a) `10^-2 V/m`

(b) `10^-4 V/m`

(c) `10^-6 V/m`

(d) `10^-8 V/m`

Answer (a)

NEET-2000

Question 95. The net resistance of the circuit between A and B is

(a) `8/3\Omega`
(b) `{14}/3\Omega`
(c) `{16}/3\Omega`
(d) `{22}/3\Omega`

Answer (b)

Question 96. A car battery of emf `12 V` and internal resistance `5\times10^-2\Omega`., receives a current of `60 amp`, from external source, then terminal potential difference of battery is

(a) `12V`
(b) `9V`
(c) `15V`
(d) `20V`

Answer (c)

Question 97. Two bulbs of `(40 W, 200 V)`, and `(100 W, 200 V)`. Then correct relation for their resistances

(a) `R_{40}<R_{100}`
(b) `R_{40}>R_{100}`
(c) `R_{40}=R_{100}`
(d) no relation can be predicted.

Answer (b)

Question 98. The potentiometer is best for measuring voltage, as

(a) it has a sensitive galvanometer and gives null deflection

(b) it has wire of high resistance

(d) it measures p.d in open circuit.

Explanation

When we measure the emf of a cell by the potentiometer then no current draws in the circuit in zero-deflection condition i.e., cell is in open circuit. Thus, in this condition the actual value of a cell is found. In this way potentiometer is equivalent to an ideal voltmeter of infinite resistance.

Note: The emf by the potentiometer is measured from null method in which zero deflection position is found on the wire.

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