91影视

Power dissipation is a measure of how much power $\left(\begin{array}{c}P=I脳V\end{array}\right)$ in a circuit is converted into heat.

The formula of power$\left(\mathrm{P}\right)$ dissipation is written as current $\left(\mathrm{I}\right)$multiply by voltage$\left(\mathrm{V}\right)$

The resistance of an ideal ammeter is 0 and the resistance of an ideal voltmeter is infinite.

So, inthe first case in figure 25.16a current passes normally since there is no extra resistance due tothe ammeter.

$\mathrm{P}=\mathrm{IV}$

But in 25.16b current doesn鈥檛 pass at all since the resistance ofthe voltmeter is infinite

$\mathrm{P}=\mathrm{IV}$

Since $\mathrm{I}=0$the equation will be

$\mathrm{P}=0$

Therefore, in fig 25.16a the bulb glows normally causingthe current to pass normally since there is no extra resistance due to the ammeter. And in fig 25.16b current doesn鈥檛 pass at all.

So, the bulb in fig 25.16a glows more brightly.