4. You are measuring the current in a circuit that is operated on an 18 V battery. The ammeter reads 40 mA. Later you notice the current has dropped to 20 mA. How much has the voltage changed?
6. If you wish to increase the amount of current in a resistor from 120 mA to 160 mA by changing the 24 V source, what should the new voltage setting be?
10. Two resistors are in series: a 5.6 kΩ resistor and a 4.7 kΩ resistor. The voltage drop across the 5.6 kΩ resistor is 10 V. The voltage across the 4.7 kΩ resistor is