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Question 1 of 36

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SAT Subject Test

The set of lettered choices below refers to multiple questions. Select the one lettered choice that best answers each question. A choice may be used once, more than once, or not at all in each set.

Which graph represents the total heat produced by a resistor carrying a steady current as a function of time from time t equals 0?

Select an Answer

Each option presents a graph. The horizontal axis is labeled Time. The origin is labeled O.  The plot is a straight line starting at the origin and extending diagonally upward to the upper right area.

Correct Answer: 
Yes

A graph shows a single sinusoidal wave, starting at the origin and extending along the horizontal axis.

Correct Answer: 
No

The plot shows a straight line parallel to the horizontal axis, starting at a point more than halfway up the vertical axis and extending to the right.

Correct Answer: 
No

A blank graph is shown.

Correct Answer: 
No

A concave up curve is shown starting near the top of the vertical axis of the graph. The curve slopes steeply down and to the right and approaches a horizontal line near the horizontal axis.

Correct Answer: 
No

The correct answer is a steadily increasing amount. The rate of heat dissipation by a resistor is equal to the power it expends. The power P is related to the current I and the resistance R by the equation P equals I to the power of 2 end exponent invisible times R, so if the current is constant the power is constant. The total heat developed is then the power multiplied by the total time t:

text Heat end text equals P t equals I squared invisible times R t.

The graph is thus a steadily increasing function of time.

Question Difficulty: 
easy