Sign in
12thPass logo
New chatPYQ LibraryDoubtsRank report
Sign in to see Recents

Your guest activity stays on this device

Sign in to save progress →
Sign in

Current Electricity question

2016 · Shift 0 · Q48
Guest · filters and generic practice availableBrowsing as a guest · PYQ filters and generic practice are available. Sign in only for personalised features and saved progress.
  1. PYQ Library
  2. /JEE Main
  3. /Physics
  4. /Current Electricity
  5. /2016 · Shift 0 · Q48

Current Electricity question

2016 · Shift 0 · Q48

JEE MainPhysicsCurrent ElectricityMCQ+4 / −1
A galvanometer having a coil resistance of 100 Ω100\,\Omega100Ω gives a full scale deflection, when a currect of 1mA1mA1mA is passed through it. The value of the resistance, which can convert this galvanometer into ammeter giving a full scale deflection for a current of 10A,10A,10A, is :
  1. A
    0.1 Ω0.1\,\Omega0.1Ω
  2. B
    3 Ω3\,\Omega3Ω
  3. C
    0.01 Ω0.01\,\Omega0.01Ω
  4. D
    2 Ω2\,\Omega2Ω
View written solutionFree

Correct answer: C

  1. Given data
  • Galvanometer resistance: G=100 ΩG = 100\,\OmegaG=100Ω
  • Full scale deflection current of galvanometer: Ig=1 mA=10−3 AI_g = 1\text{ mA} = 10^{-3}\text{ A}Ig​=1 mA=10−3 A
  • Desired ammeter full scale current: I=10 AI = 10\text{ A}I=10 A

To convert a galvanometer into an ammeter, we connect a small shunt resistance SSS in parallel with the galvanometer.

  1. Current through shunt

At full scale of the ammeter:

  • Current through galvanometer = Ig=10−3 AI_g = 10^{-3}\text{ A}Ig​=10−3 A
  • Remaining current goes through shunt:
Is=I−Ig=10−10−3=9.999 AI_s = I - I_g = 10 - 10^{-3} = 9.999\text{ A}Is​=I−Ig​=10−10−3=9.999 A
  1. Use parallel branch condition

Since galvanometer and shunt are in parallel, the potential difference across both is same:

IgG=IsSI_g G = I_s SIg​G=Is​S

Substitute values:

(10−3)(100)=(9.999)S(10^{-3})(100) = (9.999)S(10−3)(100)=(9.999)S 0.1=9.999S0.1 = 9.999S0.1=9.999S S=0.19.999≈0.010 ΩS = \frac{0.1}{9.999} \approx 0.010\,\OmegaS=9.9990.1​≈0.010Ω

So,

S≈0.01 ΩS \approx 0.01\,\OmegaS≈0.01Ω
  1. Check options
  • A: 0.1 Ω0.1\,\Omega0.1Ω ❌
  • B: 3 Ω3\,\Omega3Ω ❌
  • C: 0.01 Ω0.01\,\Omega0.01Ω ✅
  • D: 2 Ω2\,\Omega2Ω ❌

Therefore, the correct option is C.

PreviousNext

More from Current Electricity

  • In the circuit shown, the current in the 1Ω resistor is : Includes diagram2015 · MCQ
  • When 5V potential difference is applied across a wire of length 0.1m, the drift speed of electrons is 2.5×10−4ms−1. If the electron density in the wire is 8×1028m−3, the resistivity…2015 · MCQ
  • In a large building, three are 15 bulbs of 40W, 5 bulbs of 100W, 5 fans of 80W and 1 heater of 1kW. The voltage of electric mains is 220V. The minimum capacity of the main fuse of the building will be:2014 · MCQ
  • This questions has Statement - I and Statement -II. Of the four choices given after the Statements, choose the one that best describes into two Statements. Statement - I: Higher the range, greater is the…2013 · MCQ
  • The supply voltage to room is 120V. The resistance of the lead wires is 6Ω. A 60W bulb is already switched on. What is the decrease of voltage across the bulb, when a 240W heater is switched on in parallel to the bulb?2013 · MCQ
  • Two electric bulbs marked 25W−220V and 100W−220V are connected in series to a 440V supply. Which of the bulbs will fuse?2012 · MCQ
  • If a wire is stretched to make it 0.1% longer, its resistance will:2011 · MCQ
  • Two conductors have the same resistance at 0∘C but their temperature coefficients of resistance are α1​ and α2​. The respective temperature coefficients of their series and parallel combinations are nearly2010 · MCQ