A 120 V lamp-dimming circuit is controlled by a rheostat and protected from excessive current by a 3 A fuse. To what minimum resistance value can the rheostat be set without blowing the fuse? Assume a lamp resistance of 20 ohms.
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When 12 V are applied across a 68 Ω resistor, the current is
A. 816 mA
B. 17.6 mA
C. 176 mA
D. 8.16 mA
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If 24 V are applied across a resistor and there are 10.9 mA of current, the resistance is
A. 220 kΩ
B. 22 kΩ
C. 2.2 kΩ
D. 220 Ω
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Ohm's law describes how current is related to voltage and resistance.
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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?
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What is the voltage source for a circuit carrying 2 A of current through a 36 Ω resistor?
A. 1.8 V
B. 18 V
C. 7.2 V
D. 72 V
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The current through a flashlight bulb is 40 mA and the total battery voltage is 4.5 V. The resistance of the bulb is approximately
A. 112 Ω
B. 11.2 Ω
C. 1.2 Ω
D. 18 Ω
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The formula to find I
A. I = VR
B. I = V R
C. V = IR
D. I = R V
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How much resistance is required to limit the current from a 12 V battery to 3.6 mA?
A. 3.3 kΩ
B. 33 kΩ
C. 2.2 kΩ
D. 22 kΩ
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What is the approximate resistance setting of a rheostat in which 650 mA of current flows with a 150 V source?
A. 9.7 Ω
B. 97 Ω
C. 23 Ω
D. 230 Ω
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