Ohm's Law problems
- 1. What is the approximate resistance of a rheostat if the voltage source is 18 V and the current is 220 mA?
Options- A. 8.2 kΩ
- B. 820 Ω
- C. 8.2 Ω
- D. 82 Ω Discuss
Correct Answer: 82 Ω
- 2. When there is 12 mA of current through a 1.2 kΩ resistor, the voltage across the resistor is
Options- A. 14.4 V
- B. 1.4 V
- C. 100 V
- D. 10 V Discuss
Correct Answer: 14.4 V
Explanation:
V = IR (Ohms Law)
= 12 X 10-3 X 1.2 X 10 3
= 12 X 1.2
= 14.4 V
- 3. 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.
Options- A. 40 Ω
- B. 4 Ω
- C. 2 Ω
- D. 20 Ω Discuss
Correct Answer: 20 Ω
- 4. What is the voltage source for a circuit carrying 2 A of current through a 36 Ω resistor?
Options- A. 1.8 V
- B. 18 V
- C. 7.2 V
- D. 72 V Discuss
Correct Answer: 72 V
- 5. The formula to find I when the values of V and R are known is
Options- A. I = VR
- B. I = R/V
- C. V = IR
- D. I = V/R Discuss
Correct Answer: I = V/R
- 6. A resistor is connected across a 50 V source. What is the current in the resistor if the color code is red, orange, orange, silver?
Options- A. 2 mA
- B. 2.2 mA
- C. 214 mA
- D. 21.4 mA Discuss
Correct Answer: 2.2 mA
- 7. If 750 µA is flowing through 11 kΩ of resistance, what is the voltage drop across the resistor?
Options- A. 8.25 V
- B. 82.5 V
- C. 14.6 V
- D. 146 V Discuss
Correct Answer: 8.25 V
- 8. What is the approximate resistance setting of a rheostat in which 650 mA of current flows with a 150 V source?
Options- A. 9.7 Ω
- B. 97 Ω
- C. 23 Ω
- D. 230 Ω Discuss
Correct Answer: 230 Ω
- 9. Four amperes of current are measured through a 24 Ω resistor connected across a voltage source. How much voltage does the source produce?
Options- A. 960 V
- B. 9.6 V
- C. 96 V
- D. 8 V Discuss
Correct Answer: 96 V
- 10. 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
Options- A. 112 Ω
- B. 11.2 Ω
- C. 1.2 Ω
- D. 18 Ω Discuss
Correct Answer: 112 Ω
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