Electrical Components Final

A sudden increase in the total current, in a parallel circuit, as shown below, may indicate:

• A short circuit.

• A drop in source voltage.

• A blown fuse.

• An open resistor.

• None of these.

In the crankshaft position sensor, as shown below, the induced voltage across the coil is caused by …

• ... a tab passing through the magnetic field.

• ... acceleration of the steel disk’s rotational speed.

• ... rotation of the steel disk

• ... current in the coil.

• ... none of these.

110 V AC is applied across the primary winding of a transformer. When you check the voltage across the secondary winding, you get 0 V. Further investigation shows no primary or secondary currents. The cause of the malfunction is:

• The primary winding is open.

• The primary winding is completely shorted

• The primary winding is partially shorted

• The secondary winding is open

• The secondary winding is completely shorted.

A 3.3 kΩ resistor has burned out in a circuit. You must replace it with another resistor with the same resistance value. If the resistor carries 50 mA, what should be its power rating? Assume that you have available resistors in the following power ratings: ¼ W, ½ W, 1 W, 2 W, 5 W, 10 W, and 20W.

• 10 W

• 1 W

• 5 W

• ½ W

• 2 W

You are measuring the current in a circuit that is operated by a 24 V DC power supply. The ammeter measures 48 mA. Later, you notice that the current has dropped to 40 mA. Eliminating the possibility of a resistance change, you conclude that the voltage has changed. How much has the voltage of the power supply changed?

• 40 V

• 20V

• 15V

• 10V

• 25V

Which of the following statements about solenoids and relays is correct?

• A solenoid is an electromagnetically controlled device in which the mechanical movement of a plunger is activated by a magnetizing current.

• A solenoid is an electromagnetic device that converts signals to sound waves.

• A solenoid is an electromagnetically controlled mechanical device in which electrical contacts are opened or closed by a magnetizing current.

• In a solenoid the interaction of magnetic fields produces a rotation of the solenoid coil.

• None of these.

Based on the control settings, find the peak-to-peak amplitude and the period of the waveform displayed on the scope screen and calculate the frequency.

• Vpp: 0.9 V Time: 0.1ms Frequency: 10Khz

• Vpp: 0.9 V Time: 0.5ms Frequency: 2.0Khz

• Vpp: 1.8 V Time: 1ms Frequency: 1.0Khz

• Vpp: 1.8 V Time: 0.5ms Frequency: 2.0Khz

• Vpp: 2.4 V Time: 1ms Frequency: 1.0Khz

Which of the following output voltages based on the float position of an automotive fuel level sensor, as shown below, is correct?

• Full: 12 V Half Full: 6V Empty: 0V

• Full: 0V Half Full: 6V Empty: 12V

• Full: 10V Half Full: 5V Empty: 0V

• Full: 0V Half Full: 5V Empty: 10V

• Full: 8V Half Full: 4V Empty: 0V

If an object were caught in the upward movement of the car window, stalling the motor, what effect would this have on the control circuit shown below? Two answers are correct

• Increase in VR.

• Increase in IMOTOR.

• Decrease in IMOTOR.

• Increase in VR and decrease in IMOTOR.

• Decrease in VR.

For the limit switch, as shown below, the contacts are indicated by numbers. Which of the shown electrical contact symbols is correct?

• A

• B

• C

• D

• E