Circuit with Voltage-Maintaining Device · BPhO 2007 #5
Physics · electromagnetism
Problem
A 10 V battery, with negligible internal resistance, is connected to two resistors of resistance 250 Ω and 400 Ω and to the component Z as shown. Z is a device which has the property of maintaining a potential difference of 5 V across the 400 Ω resistor.
[Figure: Circuit diagram showing 10V battery connected to 250Ω resistor in series with parallel combination of 400Ω resistor and component Z]
The current through Z is
A. 2.9 mA
B. 7.5 mA
C. 12.5 mA
D. 15.4 mA