+91-8076753736[email protected]
logo
logo
-->

Moving Charges And Magnetism

Question
CBSEENPH12039951
Wired Faculty App

Two metal wires of identical dimensions are connected in series if σ1a nd σ2 are the conductivity of the metal wires respectively, the conductivity of the combination is 

  • fraction numerator 2 straight sigma subscript 1 straight sigma subscript 2 over denominator straight sigma subscript 2 space plus straight sigma subscript 2 end fraction
  • fraction numerator straight sigma subscript 1 space plus straight sigma subscript 2 over denominator 2 space straight sigma subscript 1 straight sigma subscript 2 end fraction
  • fraction numerator straight sigma subscript 1 space plus straight sigma subscript 2 over denominator straight sigma subscript 1 straight sigma subscript 2 end fraction
  • fraction numerator straight sigma subscript 1 straight sigma subscript 2 over denominator straight sigma subscript 1 space plus straight sigma subscript 2 end fraction

Solution

A.

fraction numerator 2 straight sigma subscript 1 straight sigma subscript 2 over denominator straight sigma subscript 2 space plus straight sigma subscript 2 end fraction

Net resistance of a metal wire having resistivity rho,
we have

straight R subscript 1 space equals space straight rho subscript 1 straight L over straight A similarly comma straight R subscript 2 space equals space straight rho subscript 2 straight L over straight A Then comma space net space effective space resistance space of space two space metal space wires. straight R subscript eq space equals space straight R subscript 1 space plus straight R subscript 2 rightwards double arrow space straight rho fraction numerator 2 straight L over denominator straight A end fraction space equals space straight rho subscript 1 straight L over straight A space plus straight rho subscript 2 straight L over straight A rightwards double arrow space 2 straight rho space equals space straight rho subscript 1 space plus straight rho subscript 2 As comma space conductivity space straight sigma space equals space 1 over straight rho comma space we space have 2 over straight sigma space equals space 1 over straight sigma subscript 1 space plus space 1 over straight sigma subscript 2 rightwards double arrow 2 over straight rho space equals space fraction numerator straight sigma subscript 1 plus straight sigma subscript 2 over denominator straight sigma subscript 1 straight sigma subscript 2 end fraction rightwards double arrow space Net space effective space conductivity space of space combined space wires comma straight sigma space equals space fraction numerator 2 straight sigma subscript 1 straight sigma subscript 2 over denominator straight sigma subscript 1 plus straight sigma subscript 2 end fraction

Some More Questions From Moving Charges And Magnetism Chapter

Two moving coil meters, M1 and M2 have the following particulars:
R1 = 10 Ω   N1 = 30,
A1 = 3.6 x 10–3 m2,  B1 = 0.25 T
R2 = 14 Ω;  N2 = 42,
A2 = 1.8 x 10–3 m2, B2 = 0.50 T
(The spring constants k are identical for the two meters).
Determine the ratio of (a) current sensitivity and (b) voltage sensitivity of M2 and M1.

Mock Test Series

Mock Test Series

NCERT Sample Papers

Entrance Exams Preparation