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# I have a doubt, kindly clarify. 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,

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

179 Views

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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