CD Circuits Fundamentals - BM

Which of the following statements is NOT true regarding series circuits?

• The current is the same at each point

• Total resistance is equal to the sum of the resistors

• The sum of the voltage drop will equal source voltage

• Voltage drop is inversely proportional to the size of the resistor

Answer explanation

According to Ohms Law: Voltage is directly proportional to resistance

When calculation the total resistance of a circuit, which of the following will yield a value less than the smallest resistor value?

• Combination

• Series

• Parallel

• All kinds of circuits

Answer explanation

The formula for equivalent resistance in parallel is :

1 / (1/R1 + 1/R2 + ....)

Therefore, the equivalent resistance in parallel is less than the smallest resistance. Also,

the more branches, the smallest the equivalent resistance will get.

Which of the following is not true regarding Ohm's Law?

• The resistance can be found by dividing the voltage by the current

• The voltage can be found by dividing the current by the resistance

• The voltage can be found by multiplying the current by the resistance

• The current can be found by dividing the voltage by the resistance

Answer explanation

voltage = current x resistance

Which device can be used to store an electrical charge?

• Capacitor

• Motor

• Light

• Switch

Which of the following statements is NOT correct about electromechanical relays?

• Electromechanical relays can be used to convert AC current to DC current

• Electromechanical relays are basically a magnetically operated switch

• Electromechanical relays are typically used where a lower control voltage is used to control a higher voltage load circuit

• Electromechanical relays have a coil circuit and a load/power circuit

Answer explanation

Electromechanical relays are basically a magnetically operated switch, they are typically used to control a higher voltage load circuit, and

have a coil circuit and a load/power circuit.

However, they CANNOT convert AC current to DC current

Which two laws can be used to solve electrical circuits?

• Lenz and Pascal

• Ohm and Watts

• Pascal and Kirchhoff

• Kirchhoff and Lenz

Answer explanation

Ohm's, Watt's, and Kirchhoff are used, but NOT Pascal or Lenz

Overloading a circuit can occur from ____ :

• Removing loads in parallel

• Adding more loads in parallel

• Adding more loads in series

• An open circuit

Answer explanation

Adding more loads in parallel reduces the resistance, therefore, the current increases, overloading the circuit.

Which of the following switches would be the best choice for controlling a load from two separated locations?

• Single pole double throw (SPDT)

• Double pole double throw (DPDT)

• Single pole single throw (SPST)

• Limit switch (LS)

Answer explanation

a load - single

two locations - double

Possible answers:

DPST

SPDT

A 8-W, 100-Ω resistor has a current flow of 0.2A though it. Is this resistor operating within its power rating?

• Yes, dissipates exactly 8 W

• No, dissipates 8 W

• No, dissipates only 4 W

• Yes, dissipates only 4 W

Answer explanation

The resistor is operating within its power rating as it dissipates only 4 W, which is half of its 8 W power rating when a current of 0.2A flows through it.

6 mA is equal to how many amps?

• 600

• 6,000

• 60

• 0.006

Answer explanation

1 milli is 1/1000.

6 divided by 1,000 = 0.006