EIAT Applied Electrical Calculations — Questions and Answers
Question 1: Using Ohm's Law, what is the current in a circuit with a voltage of 120 volts and a resistance of 24 ohms?
- 2,880 A
- 0.2 A
- 5 A (Correct answer)
- 144 A
Correct answer: 5 A
Ohm's Law: I = V ÷ R. Current = 120 ÷ 24 = 5 amperes. Ohm's Law relates voltage (V), current (I), and resistance (R) with the formula V = I × R.
Question 2: Two resistors of 8 ohms each are connected in series. What is the total resistance?
- 4 ohms
- 16 ohms (Correct answer)
- 8 ohms
- 64 ohms
Correct answer: 16 ohms
In a series circuit, resistances add directly: R_total = R1 + R2 = 8 + 8 = 16 ohms. Current must flow through each resistor in sequence, so their resistance values accumulate.
Question 3: An elevator motor operates at 240 volts and draws 20 amperes of current. What is its power consumption in watts?
- 12 watts
- 260 watts
- 4,800 watts (Correct answer)
- 220 watts
Correct answer: 4,800 watts
Power (P) = Voltage (V) × Current (I). P = 240 × 20 = 4,800 watts. Power is measured in watts and represents the rate at which electrical energy is consumed.
Question 4: A wire with a resistance of 2 ohms carries a current of 6 amperes. What is the voltage drop across the wire?
- 3 V
- 0.33 V
- 36 V
- 12 V (Correct answer)
Correct answer: 12 V
Using Ohm's Law: V = I × R = 6 × 2 = 12 volts. The voltage drop across the wire represents energy lost to resistance in that conductor.
Question 5: Two resistors of 6 ohms and 3 ohms are connected in parallel. What is the total resistance?
- 9 ohms
- 0.5 ohms
- 2 ohms (Correct answer)
- 18 ohms
Correct answer: 2 ohms
For parallel resistors: 1/R_total = 1/R1 + 1/R2 = 1/6 + 1/3 = 1/6 + 2/6 = 3/6 = 1/2. Therefore R_total = 2 ohms. Parallel circuits provide multiple current paths, reducing total resistance.
Question 6: A 480-watt motor runs on 120 volts. What current does it draw?
- 57,600 A
- 360 A
- 4 A (Correct answer)
- 360 A
Correct answer: 4 A
Rearranging the power formula P = V × I gives I = P ÷ V. Current = 480 ÷ 120 = 4 amperes. This is a common calculation when sizing wiring or breakers for electrical equipment.
EIAT Applied Electrical Calculations
Using Ohm's Law, what is the current in a circuit with a voltage of 120 volts and a resistance of 24 ohms?