Series and parallel resistor circuits with 3 problems

[mustang]

Problem 17.
A(n) 5.2 ohm resistor, a(n) 9.2 ohm resistor, and a(n) 14 ohm resistor are connected in series with 6.0V battery.
Determine the equivalent resistance for the circuit. Answer in units of ohms.
Note: I don't know where to start.

Problem 26.
A resistor with an unknown resistance is connected in parallel to a(n) 14 ohm resistor. When both resistors are connected in parallel to an emf source of 19 V, the current across the unknown resistor is measured with an ammeter to be 3.2 A.
What is the resistance of the unknown resistor? In units of ohm.
Note: What formula(s) should I use?

Problem 27.
Two resistors, A and B, are connected in series to a 12 V battery. A voltmeter connected across resistor A measures a potential difference of 6.7 V. When the two resistors are connected in parallel across the 12 V battery, the current in B is found to be 1.6 A. Find the resistance of B. Answer in ohms.
Note: What formula(s) should I use?

 

[chroot]

Same as your other thread. Start with the fact that when you wire resistors in series, their resistances add together.

- Warren

 

[M98Ranger]

For Problem 17, you can use the formula for equivalent resistance in a series circuit, which is R_eq = R1 + R2 + R3. So in this case, R_eq = 5.2 ohms + 9.2 ohms + 14 ohms = 28.4 ohms. The equivalent resistance for the circuit is 28.4 ohms.

For Problem 26, you can use the formula for current in a parallel circuit, which is I = (V/R). You know the current (3.2 A), voltage (19 V), and one of the resistances (14 ohms). So you can rearrange the formula to solve for the unknown resistance (R). R = V/I = 19 V/3.2 A = 5.9375 ohms. The resistance of the unknown resistor is 5.9375 ohms.

For Problem 27, you can use the formula for current in a series circuit, which is I = V/R. You know the voltage (12 V), current (1.6 A), and one of the resistances (6.7 V). So you can rearrange the formula to solve for the unknown resistance (R). R = V/I = 6.7 V/1.6 A = 4.1875 ohms. The resistance of B is 4.1875 ohms.