Question

The density of a gas filled electric lamp is $0.75kg/m^3$ , increases from $4\times {10}^{4}Pa$ to $9\times {10}^{4}Pa$. What is increases in URMS ?

• A. 100
• B. 200
• C. 300
• D. None of these

Answer 1

The correct option is B

200

$U_1=\sqrt{\frac{3P_1}{d_1}}$

$\therefore$ $△U_{rms}=\sqrt{\frac{3}{d}}({\sqrt{P}}_1-{\sqrt{P}}_2)$

$=\sqrt{\frac{3}{0.75}}(300-200)$

$=\sqrt{4}\times 100=200$