Lesson 5: Electrical Principals

Question 1

Why are metals generally good conductors of electricity?

A. They have relatively high density

B. They have many free electrons

C. They have many free protons

D. All these choices are correct

Answer 1

B. They have many free electrons

Question 2

What formula is used to calculate current in a circuit?

A. I = E x R

B. I = E / R

C. I = E + R

D. I = E - R

Answer 2

B. I = E / R

Note:
Using Ohm’s Law, I (current) equals E (voltage) divided by R (resistance), or I = E / R.

Question 3

What does the abbreviation “RF” mean?

A. Radio frequency signals of all types

B. The resonant frequency of a tuned circuit

C. The real frequency transmitted as opposed to the apparent frequency

D. Reflective force in antenna transmission lines

Answer 3

A. Radio frequency signals of all types

Question 4

Which of the following is a good electrical insulator?

A. Copper

B. Glass

C. Aluminum

D. Mercury

Answer 4

B. Glass

Question 5

Which is equal to 500 milliwatts?

A. 0.02 watts

B. 0.5 watts

C. 5 watts

D. 50 watts

Answer 5

B. 0.5 watts

Note:
1 watt = 1000 milliwatts. Thus, 1/2 (0.5) watt = 500 milliwatts.

Question 6

Electrical current is measured in which of the following units?

A. Volts

B. Watts

C. Ohms

D. Amperes

Answer 6

D. Amperes

Question 7

How much power is delivered by a voltage of 12 volts DC and a current of 2.5 amperes?

A. 4.8 watts

B. 30 watts

C. 14.5 watts

D. 0.208 watts

Answer 7

B. 30 watts

Note:
These are the key pieces of information needed to solve this problem. How much power is being used in a circuit when the applied voltage is 12 volts DC and the current is 2.5 amperes? They are looking for power, you are given 12 volts DC and you are given 2.5 amperes. Looking at Ohm’s Law, we quickly see that amps times volts equals power. Thus, 12 volts multiplied by 2.5 amperes equals 30 watts, or 12 x 2.5 = 30.

Question 8

Which is equal to one kilovolt?

A. One one-thousandth of a volt

B. One hundred volts

C. One thousand volts

D. One million volts

Answer 8

C. One thousand volts

Question 9

Which is equal to 2425 MHz?

A. 0.002425 GHz

B. 24.25 GHz

C. 2.425 GHz

D. 2425 GHz

Answer 9

C. 2.425 GHz

Note:
1000 MHz = 1 GHz. 2425 MHz = 2.425 GHz.

Question 10

What is the current through a 100-ohm resistor connected across 200 volts?

A. 20,000 amperes

B. 0.5 amperes

C. 2 amperes

D. 100 amperes

Answer 10

C. 2 amperes