38. In a circuit consisting of a battery and a resistor with a resistance of 10 Ohms, a voltmeter is first connected in series and then parallel to a resistor with resistance R. Both voltmeter readings are the same. The resistance of the voltmeter is 1000 Ohms. What is the internal resistance of the battery?

Detailed solution. Decorated in Microsoft Word 2003. (Target decided to use formula editor)