Practice Problems: Short Circuits
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1. (moderate) Given standard lab equipment, how would you determine the emf and the internal resistance of a standard flashlight battery? Write a procedure that could be followed by a fellow student.

2. (moderate) A single loop circuit consists of a battery (10 v with 1 Ω of internal resistance) and a load resistor (100 Ω). A single piece of wire is also available that can short circuit the battery. Determine the terminal voltage of the battery before and after the short is applied.

3. (easy) A flashlight battery (emf of 1.5 v) is shorted with a wire of almost zero resistance. The current in the wire is 28 A. Find the internal resistance of the battery.

4. (moderate) A 2.0 Ω resistor is attached across a 12 v battery. The terminal voltage is measured to be 8.5 v. What is the internal resistance of the battery?

5. (moderate) A simple circuit consists of a 12 v battery (whose internal resistance is 0.1 Ω) and a 100 Ω resistor. Compare the power dissipated by the battery before and after it is short-circuited.

6. (hard) The sketch below shows two batteries (with internal resistance) connected to a load resistor. If the internal resistance of the lower battery is 0.016Ω and that of the upper battery is 0.012Ω, determine the resistance (R) if one of the batteries was found to have no terminal voltage. Also determine which battery can show this condition.


7. (hard) A battery (r = 0.5Ω) is connected to x number of lightbulbs (each the same with R = 15 Ω). The bulbs are all connected in parallel with the battery. The terminal voltage is measured to be ½ the emf. Find x.

Please supplement these problems with those found in your companion text.