# Basic Electric Concepts

February 1, 2008

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**The electric property that represents the electrical “pressure” across two points in a circuit is called:**

a. current.

b. resistance.

c. voltage.

d. power.

**The electric property that represents the amount of electricity moving in a circuit is called:**

a. current.

b. resistance.

c. voltage.

d. power.

**The electric property that represents the opposition to electricity moving in a circuit is called:**

a. current.

b. resistance.

c. voltage.

d. power.

**If you connect four 1K resistors in series, what is the total resistance of the circuit?**

a. 1,000

b. 2,000

c. 3,000

d. 4,000

**The VA rating of a transformer tells you how much power it is capable of delivering.**

a. True

b. False

**If you connect four 1K resistors in parallel, what is the total resistance of the circuit?**

a. 250

b. 500

c. 1,000

d. 4,000

**Connecting batteries in series increases the overall voltage.**

a. True

b. False

**What is the resistance of a resistor with brown, black, and red bands?**a. 100

b. 200

c. 1,000

d. 2,200

**If the fourth band of a resistor is gold, then its tolerance is 10 percent.**

a. True

b. False

**In order to test a fuse, you must remove it from the circuit.**

a. True

b. False

**What are the first 3 bands of a 2.2K resistor?**

a. brown, black, red

b. red, red, red

c. brown, red, black

d. black, brown, red

e. brown, brown, brown

**Standard electrical power in the United States operates on a frequency of 60 Hz.**

a. True

b. False

**Ohm’s law can be expressed as voltage = current x resistance.**a. True

b. False

**The voltage drop of a circuit is determined by the resistance of the wire and the current flow.**

a. True

b. False

**How much current will flow in a circuit with a 12 VDC source connected to a 1K load?**

a. 12 amps

b. 1.2 amps

c. 0.12 amps

d. 0.012 amps

## Whatâ€™s Wrong with This?

Wally `Larman installed an access system that used a magnetic lock on one door. He needed to check the amount of current the lock was drawing so that he could troubleshoot a system problem. To do this, Wally took out his volt Ohm meter (VOM) and connected it as shown in this diagram, but was unable to read the current draw. Can you see what Wally did wrong and what he must do to correct the problem?## 5-Minute Tech Quiz Answers

1. c2. a

3. b

4. d â€” When connecting resistors in series, the total resistance is the sum of all of the resistors in the circuit. In this case, 1K + 1K + 1K + 1K = 4K, which is 4,000 ohms.

5. a â€” The VA rating shows the voltage x current available. Because power can be simply represented by voltage x current, the higher the VA rating, for a fixed voltage, the higher the current available.

6. a

7. a â€” Connecting batteries in series will increase the overall voltage. Connecting batteries of the same voltage in parallel increases the available standby time.

8. c

9. b â€” Gold represents a tolerance of 5 percent. Silver’s tolerance is 10 percent.

10. b â€” You can test a fuse in circuit by setting your meter on voltage and placing the leads across the fuse. If the fuse is good, you will read 0 volts.

11. b

12. a

13. a â€” This formula can be used to calculate any item as long as you have the remaining two values.

14. a

15. d â€” According to Ohm’s law (voltage = current x resistance), 12 = current x 1000, or current = 12/1000, which equals 0.012 amps. This also can be referred to as 12 mA.