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Introduction to SAT II Physics - FreeExamPapers

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The equivalent resistance,<br />

, of two identical resis<strong>to</strong>rs in parallel is given by the formula:<br />

The equivalent resistance of three identical resis<strong>to</strong>rs in parallel is given by the formula:<br />

The ratio, then, between the new resistance and the old is:<br />

6. D<br />

According <strong>to</strong> Ohm’s Law, V = IR, current and resistance are inversely proportional. In the previous question,<br />

we saw that the new resistance is 2 / 3 the old resistance. That means that, inversely, the new current is 3 / 2<br />

times the old resistance.<br />

7. E<br />

The power dissipated in a resis<strong>to</strong>r is given by the formula P = I 2 R, which in this case has a value of 20 W. The<br />

heat dissipated in a resis<strong>to</strong>r is given by the formula H = Pt: every second, the resis<strong>to</strong>r dissipates 20 J of<br />

heat. Since we are looking at a 10-second period, the <strong>to</strong>tal heat dissipated is 200 J.<br />

8. A<br />

The equivalent capacitance of two capaci<strong>to</strong>rs in series is:<br />

244

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