Programmed Review for Electrical Engineering, Third Edition
This text contains an organized review of the basic electrical engineering fundamentals, with 111 problems, solutions and explanations for the core electrical engineering concepts.
TABLE OF CONTENTS Programmed Review for Electrical Engineering, Third Edition
Capacitors
The problems in this section illustrate the fundamental properties of capacitor energy and charge.
Problem 2-7: CAPACITOR ENERGY AND CHARGE
Q:
The current waveform shown below approximates a current impulse. If this pulse is applied to a capacitor, determine:
how much energy is applied to the capacitor;
how much charge it accepts.
Answers
Q:
Equations required for solution are:
Solving for capacitor voltage:
Therefore,
(answer)
W =
(4) 2 = 8 10 -7 joule
(answer)
Q = 4 10 -7 coulomb
If your solution is correct, go on to Problem 2-8.
If your solution is not correct, review pp. 2, 3, 6 and 7.
Problem 2-8: TWO-CAPACITOR CHARGE TRANSFER
Q:
In the circuit shown below, the two capacitors are charged to the given initial conditions prior to switch closure. The value of the resistor is 0 < R < ?.
Initial conditions:
Determine for the two capacitors the final values for:
voltage;
charge;
energy;
the energy dissipated as heat in the resistor after the switch has been closed for a long time.
Answers
Q:
After the switch is closed, current will flow in the circuit until the two capacitors reach the same voltage (somewhere between 25 and 100). The length of time current flows is dependent, in part, upon the value of R. No matter what value R is, it will eventually dissipate a fixed amount of energy as heat. Since no energy is being added to...
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