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QJEEM17Phe699: JEE Main 2017 Physics - Class 12 JEEM17Phe699 Solution: In a meter bridge experiment resistances are connected as shown …

In a meter bridge experiment resistances are connected as shown in the figure. Initially resistance P = 4 Ω and the neutral point N is at 60 cm from A. Now an unknown resistance R is connected in series to P and the new position of the neutral point is at 80 cm from A. The value of unknown resistance R is :

JEE Main 2017 (Online) 9th April Morning Slot Physics - Current Electricity Question 278 English

Multiple Choice Options

  • A 335Ω
  • B 6 Ω
  • C 7 Ω
  • D 203Ω

Step-by-Step Verified Solution

Initially, the resistance P = 4 Ω and the neutral point N is at 60 cm from A. Therefore,

460=Q40⇒Q=16060=(83)Ω

When an unknown resistance R is connected in series to P and the new position of the neutral point is at 80 cm from A, we have

4+R80=Q20

⇒4+R80=860⇒4+R=646

⇒R=646−4=64−246=406

⇒R=(203)Ω

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