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Changing voltage The voltage V (volts), current I
Chapter 3, Problem 15E(choose chapter or problem)
Problem 15E
Changing voltage The voltage V (volts), current I (amperes), and resistance R (ohms) of an electric circuit like the one shown here are related by the equation V = IR.Suppose that V is increasing at the rate of 1 volt sec while I is decreasing at the rate of 1 3 amp sec. Let t denote time in seconds.
a. What is the value of dV/dt?
b. What is the value of dV/dt?
c. What equation relates dR/dt to dV/dt and dI/dt?
d. Find the rate at which R is changing when V = 12 volts and I = 2 amp. Is R increasing, or decreasing?
Questions & Answers
QUESTION:
Problem 15E
Changing voltage The voltage V (volts), current I (amperes), and resistance R (ohms) of an electric circuit like the one shown here are related by the equation V = IR.Suppose that V is increasing at the rate of 1 volt sec while I is decreasing at the rate of 1 3 amp sec. Let t denote time in seconds.
a. What is the value of dV/dt?
b. What is the value of dV/dt?
c. What equation relates dR/dt to dV/dt and dI/dt?
d. Find the rate at which R is changing when V = 12 volts and I = 2 amp. Is R increasing, or decreasing?
ANSWER:
Solution
Step 1 of 2
Here it is given that
(a) V is increasing at that rate of 1 volt/sec
So,
.
Positive because V is increasing .
(b) I is decreasing at the rate of
So,
Negative because I is decreasing.