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Four identical electrical lamps are labelled 1.5V, 0.5A which describes the condition necessary for them to operate at normal brightness. A 12V battery of negligible internal resistance is connected to lamps as shown, then

  • Option 1)

    The value of R for normal brightness of each lamp is  \frac{3}{4} \Omega

  • Option 2)

    The value of R for normal brightness of each lamp is \frac{21}{4} \Omega

  • Option 3)

    Total power dissipated in circuit when all lamps are normally bright is 24W

  • Option 4)

    Power dissipated in R is 21W when all lamps are normally bright

 

Answers (1)

best_answer

V = IR   \Rightarrow R=3 \Omega

For normal brightness current through each bulb is 0.5 A

Therefore, Total current = 2A

I=\frac{21}{4} \Omega


Option 1)

The value of R for normal brightness of each lamp is  \frac{3}{4} \Omega

Incorrect

Option 2)

The value of R for normal brightness of each lamp is \frac{21}{4} \Omega

Correct

Option 3)

Total power dissipated in circuit when all lamps are normally bright is 24W

Incorrect

Option 4)

Power dissipated in R is 21W when all lamps are normally bright

Incorrect

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divya.saini

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