Navigate

A potentiometer wire of length 100cm has a resistance of 10Ω. It is connected in series

A potentiometer wire of length 100cm has a resistance of 10Ω. It is connected in series with a resistance and a cell of emf 2V having negligible internal reistance. A source of emf 10 mV is balanced against a length of 40 cm of the potentiometer wire.The value of external resistance is

Options

(a) 760Ω
(b) 640Ω
(c) 790Ω
(d) 840Ω

Correct Answer:

790Ω

Explanation:

No explanation available. Be the first to write the explanation for this question by commenting below.

UP2015
admin:

View Comments (1)

  • Let the resistance be r and current be I .According to loop rule :
    E=V+Ir
    2=I(10+r)
    And also
    I*(40/100)=0.01V
    Here you get I=2.5*10^-3ampere
    Put this Vue in eqn 2=I(10+r) and get solution

Leave a Comment

Related Questions

  1. A particle moves a distance x in time but according to equation x=(t+5)⁻¹
  2. A long wire carrying a steady current is bent into a circular loop of one turn.
  3. The self-inductance of a choke coil is 10 mH. When it is connected with a 10 V DC source,
  4. A boy standing at top of a tower of 20 m height drops a stone
  5. An amplifier has a voltage gain Av=1000. The voltage gain in dB is