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# Direct Current Practice Test

(not rated)
By McGraw-Hill Professional
Updated on Sep 15, 2011

Review the following concepts if needed:

## Direct Current Practice Test

A good score is eight correct. Answers are given at the end.

1. Suppose that 5.00 × 10 17 electrical charge carriers flow past a point in 1.00 s. What is the electrical voltage?

(a) 0.080 V

(b) 12.5 V

(c) 5.00 V

(d) It cannot be calculated from this information.

2. An ampere also can be regarded as

(a) an ohm per volt.

(b) an ohm per watt.

(c) a volt per ohm.

(d) a volt-ohm.

3. Suppose that there are two resistances in a series circuit. One of the resistors has a value of 33 kΩ (that is, 33,000 or 3.3 × 10 4 ohms). The value of the other resistor is not known. The power dissipated by the 33-kΩ resistor is 3.3 W. What is the current through the unknown resistor?

(a) 0.11 A

(b) 10 mA

(c) 0.33 mA

(d) It cannot be calculated from this information.

4. If the voltage across a resistor is E (in volts) and the current through that resistor is I (in milliamperes), then the power P (in watts) is given by the following formula:

(a) P = EL

(b) P = EI × 10 3 .

(c) P = EI × 10 −3 .

(d) P = E/I .

5. Suppose that you have a set of five 0.5-W flashlight bulbs connected in parallel across a dc source of 3.0 V. If one of the bulbs is removed or blows out, what will happen to the current through the other four bulbs?

(a) It will remain the same.

(b) It will increase.

(c) It will decrease.

(d) It will drop to zero.

6. A good dielectric is characterized by

(a) excellent conductivity.

(b) fair conductivity.

(c) poor conductivity.

(d) variable conductivity.

7. Suppose that there are two resistances in a parallel circuit. One of the resistors has a value of 100 ohms. The value of the other resistor is not known. The power dissipated by the 100-ohm resistor is 500 mW (that is, 0.500 W). What is the current through the unknown resistor?

(a) 71 mA

(b) 25 A

(c) 200 A

(d) It cannot be calculated from this information.

8. Conventional current flows

(a) from the positive pole to the negative pole.

(b) from the negative pole to the positive pole.

(c) in either direction; it doesn’t matter.

(d) nowhere; current does not flow.

9. Suppose that a circuit contains 620 ohms of resistance and that the current in the circuit is 50.0 mA. What is the voltage across this resistance?

(a) 12.4 kV

(b) 31.0 V

(c) 8.06 × 10 −5 V

(d) It cannot be calculated from this information.

10. Which of the following cannot be an electric charge carrier?

(a) A neutron

(b) An electron

(c) A hole

(d) An ion

1. d

2. c

3. b

4. c

5. a

6. c

7. d

8. a

9. b

10. a

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