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A circuit is set up as shown - Scottish Highers Physics - Question 19 - 2016

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Question 19

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A circuit is set up as shown. The resistance of the variable resistor is increased and corresponding readings on the ammeter are recorded. Resistance (Ω) Current ... show full transcript

Worked Solution & Example Answer:A circuit is set up as shown - Scottish Highers Physics - Question 19 - 2016

Step 1

A. increases

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Answer

As the resistance increases, the current through the resistor decreases according to Ohm's Law (I=VRI = \frac{V}{R}) since the voltage remains constant at 12V. Thus, the power dissipated (given by P=I2RP = I^2R) will not increase.

Step 2

B. decreases

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Answer

The power does not simply decrease consistently; it first decreases as resistance increases and later trends upward again at higher resistances due to the squared term in the power formula.

Step 3

C. remains constant

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Answer

The power dissipated cannot remain constant, as it varies with changes in resistance and hence current.

Step 4

D. decreases and then increases

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Answer

This choice aligns more closely with the behavior observed in the data collected; as resistance increases, the current decreases initially, causing power to drop, but at very high resistances, the power may slightly increase depending on the current for specific resistances.

Step 5

E. increases and then decreases

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Answer

This option does not accurately describe the trend observed from the data. The power does not initially increase with resistance.

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