GROL Electrical Principles and Units 5

Question 1

A power amplifier has a 1-watt input and a 100-watt output. What is the power gain in dB?

Accepted Answer

20 dB

Answer

Gain(dB) = 10 × log(Pout/Pin) = 10 × log(100) = 10 × 2 = 20 dB.

Question 2

A voltage gain of 10 times corresponds to how many dB?

Accepted Answer

20 dB

Answer

Gain(dB) = 20 × log(Vout/Vin) = 20 × log(10) = 20 × 1 = 20 dB.

Question 3

A transformer has 1000 primary turns and 100 secondary turns. If the primary voltage is 120 V, what is the secondary voltage?

Accepted Answer

12 V

Answer

Vs = Vp × (Ns/Np) = 120 × (100/1000) = 12 V.

Question 4

A step-down transformer has 1000 primary turns and 100 secondary turns. If the secondary delivers 10 A to a load, what is the primary current (assume 100% efficiency)?

Accepted Answer

1 A

Answer

Ip = Is × (Ns/Np) = 10 × (100/1000) = 1 A; current transforms inversely to voltage.

Question 5

What is the time constant of a series RC circuit with R = 10 kΩ and C = 0.1 μF?

Accepted Answer

1 ms

Answer

τ = RC = 10,000 × 0.0000001 = 0.001 s = 1 ms.

(GROL) General Radiotelephone Operator License Practice Test

(GROL) General Radiotelephone Operator License Practice Test

GROL Electrical Principles and Units 5