Page 318 - Schaum's Outline of Theory and Problems of Applied Physics

CHAP. 25] DIRECT-CURRENTCIRCUITS 303

Multiple-Choice Questions

25.1. A resistor R connected to a battery dissipates energy at the rate P. If another resistor is connected in parallel with
R, the power dissipated by R is
(a) less than P (c) more than P
(b) P (d) any of the above, depending on the values of the resistances

25.2. The second resistor of Question 25.1 is connected in series with R. The power dissipated by R is now
(a) less than P (c) more than P
(b) P (d) any of the above, depending on the values of the resistances

25.3. A network is being analyzed using Kirchhoff’s rules. If the wrong direction is assumed for one of the currents I, the
calculated current will be
(a) 0 (c) I
(b) −I (d) incorrect

25.4. A 60-V potential difference is applied across a 5- and a 10- resistor in series. The current in the 5- resistor is
(a) 4 A (c) 12 A
(b) 6 A (d) 18 A

25.5. The potential difference across the 5- resistor in Question 25.4 is
(a) 20 V (c) 40 V
(b) 30 V (d) 60 V

25.6. A5- resistor and a 10- resistor are connected in parallel. Their equivalent resistance is
(a) 0.3 (c) 7.5
(b) 3.3 (d) 15

25.7. A 60-V potential difference is applied across the resistors of Question 25.6. The current in the 5- resistor is
(a) 4 A (c) 12 A
(b) 6 A (d) 18 A
25.8. The equivalent resistance of two identical resistors in parallel is 10 . The equivalent resistance of the same resistors
in series would be
(a) 10 (c) 40
(b) 20 (d) 100

25.9. A network of three 5- resistors cannot have an equivalent resistance of
(a) 1.67 (c) 7.5
(b) 2.5 (d) 15

25.10. A battery of emf 12 V whose internal resistance is negligible is connected across a 10- resistor in parallel with a
resistor of resistance R. If the battery current is 2 A, the value of R is

(a) 3.75 (c) 15
(b) 6 (d) 20

25.11. A current of 9 A flows when a 120-V battery is connected across a 12- resistor. The battery has an internal resistance
of
(a) 1.3 (c) 13.3
(b)12 (d) 25.3