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. Given the value of Rydberg constant is 10⁷ m⁻¹, the wave number of the last line
  2. A radiotransmitter radiates 1 kW power at a wavelength 198.6 m. How many photons
  3. A solenoid of length l metre has self inductance L henry. If number of turns
  4. A potentiometer wire has length 4m resistance 8Ω. The resistance that must be connected
  5. A body has 80 microcoulomb of charge. Number of additional electrons in it will be