Page 319 - Schaum's Outline of Theory and Problems of Applied Physics

304 DIRECT-CURRENTCIRCUITS [CHAP. 25

25.12. A battery of emf 12 V and internal resistance 1 is connected across a 3- resistor. The potential difference across
the resistor is
(a) 2.25 V (c) 9 V
(b) 3 V (d) 12 V

25.13. A5- resistor and a 10- resistor are connected in series to a battery. If heat is produced in the 5- resistor at the
rate P, the rate at which heat is produced in the 10- resistor is
(a) P/4 (c) P
(b) P/2 (d) 2P

25.14. A5- resistor and a 10- resistor are connected in parallel to a battery. If heat is produced in the 5- resistor at
the rate P, the rate at which heat is produced in the 10- resistor is
(a) P/4 (c) P
(b) P/2 (d) 2P

Supplementary Problems

25.1. It is desired to have a current of 20 A in a 5- resistor when it is connected to an 80-V battery. Is there any way in
which an auxiliary resistor can be connected in the circuit to increase the current in the 5- resistor to this value? If
so, what should its resistance be?

25.2. (a) Find the equivalent resistance of four 60- resistors connected in series. (b) If a potential difference of 12 V is
applied across the combination, what is the current in each resistor?

25.3. (a) Find the equivalent resistance of four 60- resistors connected in parallel. (b) If a potential difference of 12 V
is applied across the combination, what is the current in each resistor?

25.4. You have three 2- resistors. List the various resistances you can provide with them.

25.5. A 100- and a 200- resistor are connected in series with a 40-V power source. (a) What is the current in each
resistor? (b) How much power does each one dissipate?

25.6. A 100- and a 200- resistor are connected in parallel with a 40-V power source. (a) What is the current in each
resistor? (b) How much power does each one dissipate?

25.7. What resistance should be connected in parallel with a 1000- resistor to produce an equivalent resistance of 200 ?

25.8. A5- resistor is connected in parallel with a 15- resistor. When a potential difference is applied to the combination,
which resistor will carry the greater current? What will the ratio of the currents be?

25.9. A 25-, a 40-, and a 60- resistor are in series in a circuit such that the voltage across the 25- resistor is 18 V. Find
(a) the voltage across the other resistors and (b) the current in each.

25.10. (a) Find the equivalent resistance of the circuit shown in Fig. 25-14. (b) If a potential difference of 20 V is applied
to the circuit, find the current in each resistor.

25.11. (a) Find the equivalent resistance of the circuit shown in Fig. 25-15. (b) If a potential difference of 100 V is applied
to the circuit, find the current in each resistor.
25.12. (a) Find the equivalent resistance of the circuit shown in Fig. 25-16. (b) A 6-V battery whose internal resistance is
1 is connected to the circuit. Find the current in each resistor.