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I'm given a question and part (1 asks me to find the total resistance of a 3.0 and 6.0 ohm resistor when I) in series and ii) In parallel. The answers to those are 9 ohms and 2 ohms respectively.

Now, part B) says that a 4.0 ohm and 6.0v battery of negligible internal resistance are connected in series with the combination In (a)

I sketched a circuit

Now it wants me to find the current, p.d., and power dissipated on each resitor but I'm not sure how. I tried several attempt but they've not been successful.

Thanks.

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  • \$\begingroup\$ the current in a series circuit is the same at all points in that circuit which applies to the diagram shown. \$\endgroup\$
    – Solar Mike
    Nov 6 '17 at 9:15
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    \$\begingroup\$ Intersting in that some of us provide hints to get the OP to improve, others just shove out the answer.... \$\endgroup\$
    – Solar Mike
    Nov 6 '17 at 9:17
  • \$\begingroup\$ "a 6.0 v battery and 4.0 ohm resistor of negligible internal resistance" doesn't make sense. The part "of negligible internal resistance" must belong to battery. A resistor of negligible internal resistance is nonsence. \$\endgroup\$
    – Curd
    Nov 6 '17 at 10:03
  • \$\begingroup\$ Yes sorry it was the other way @Curd \$\endgroup\$
    – Neamus
    Nov 6 '17 at 10:13
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The only voltage source in the system is the 6V battery, so use \$\frac{V}{R_1+R_2+R_3}\$ to find the current \$I\$ going through each resistor.

Now \$V=IR\$ and \$P = IV\$. You can substitute to get \$P = I^2 × R\$. You can now find the power dissipated by each resistor.

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First find the equivalent resistance of the three resistors (in series, so add the resistances). Next, find the circuit current, you now know the load resistance and the battery voltage, so you can use ohm's law to calculate the current. The resistors are in series, so the current in each resistor is the same. Now you know the current and resistance of each resistor, you can use ohm's law to calculate the voltage drop across each resistor (add them all up and make sure the total is 6V). You now know the voltage and current in each resistor, multiply the two to get power. You can also use one the form of ohm's law that relates power to resistance and current and do the last two steps in a single formula.

If you make an attempt at the procedure above and show your work, I'll help you verify your answer and correct any mistakes.

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This will be answered with Ohm's law and Watt's law. I'm sure your textbook has one chapter devoted to each law.

Hint

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