[FAA] FAA题库之General

001. What may result if water is added to a nickel-cadmium battery when it is not fully charged?

         Excessive spewing is likely to occur during the charging cycle
The level of the electrolyte in a nickel-cadmium cell changes as it is discharged and charged. The level is lowest when the cell is discharged and highest at the end of the charging cycle.
If water is added to a cell when some of the electrolyte has been absorbed into the plates, the level will be too high when the cell is fully charged. Some of this excess liquid will spew out of the cell when it is near the end of its charge cycle.

002. What is the operating resistance of a 30-watt light bulb designed for a 28-volt system?

         26 ohms
A 30-watt light bulb operating in a 28-volt electrical system has a hot resistance (operating resistance) of 26.13 ohms.
R = E^2 ÷ P
= 28^2 ÷ 30
= 26.12 omega

003. (Refer to Figure 19.) When the landing gears are up and the throttles are retarded, the warning horn will not sound if an open occurs in wire
       No.6
Wire 6 is in the ground circuit for the landing gear warning horn. The horn will not sound if there is an open in this wire when the throttles are retarded and the landing gears are up. Wire 5 is not in the warning horn ground circuit when the right landing gear is up. Wire 7 is not in the warning horn ground circuit.

004. (Refer to Figure 12.) Find the total resistance of the circuit.

             21.2 ohms
This problem can be solved in four steps:
1. Combine resistors R(4) and R(5) in parallel.
2. Combine resistor R(2) with R(4-5) in series.
3. Combine resistors R(2-4-5) with R(3) in parallel.
4. Combine resistors R(2-3-4-5) with R(1) in series.

006. (Refer to Figure 15.) The No. 7 wire is used to

         Close the PUSH-TO-TSET circuit
Wire No. 7 supplies power to both the red and green indicator lights from the 5-amp circuit breaker. When either of the press-to-test lamps is pushed, the circuit is completed to ground, allowing the lamp to light up as long as it remains pressed. Press-to-test lamps are used to allow the pilot to ascertain that the bulb in the lamp is good.

021. (Refer to Figure 15.) With the landing gear retracted, the red indicator light will not come on if an open occurs in wire

            N0.19
With the landing gear retracted, the red indicator light will not come on if there is an open in wire No. 19. Wire No. 19 supplies power from the bus to the red indicator light, through the up-limit switch and through wire No. 8. Wire No. 7 supplies power to the red indicator light for the press-to-test circuit. Wire No. 17 supplies power to the green indicator light for its press-to-test circuit.

058. (Refer to Figure 15.) When the landing gear is down, the green light will not come on if an open occurs in wire

        No.6
The green light will not come on when the landing gear is down if there is an open in wire No. 6. (Note: The switches in Figure 15 are shown in the position for the gear down and the airplane on the ground.) Wire No. 7 supplies power to both the red and green indicator lights from the 5-amp circuit breaker for the push-to-test circuit. Wire No. 17 supplies power to the green indicator light for its push-to-test circuit.

005. A thermal switch, or thermal protector, as used in an electric motor, is designed to

         open the circuit in order to allow cooling of the motor
A thermal switch is another name for a built-in thermal circuit breaker. This is a circuit protection device that opens the circuit when the windings of the motor get too hot. If the motor overheats for any reason, the thermal switch will open the power circuit to the motor and allow the motor to cool.

007. When different rated capacitors are connected in parallel in a circuit, the total capacitance is
(Note: C(T) = C(1) + C(2) + C(3) . . .)

          Equal to the sum of all the capacitances
When capacitors are connected in parallel, the effective area of the plates add, and the total capacitance is the sum of the individual capacitances.

008. The presence of any small amount of potassium carbonate deposits on the top of nickel-cadmium battery cells in service is an indication of

         Normal operationWhen a nickel-cadmium battery is fully charged, the battery becomes hot and the electrolyte bubbles. This causes some of the electrolyte to spew out of the top of the cell