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WorksheetsSiemens Level 1 Electrical #1
Total questions: 20
Worksheet time: 40mins
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.
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
In a voltage divider circuit, as shown below, the individual measured voltage drops across resistors R1, R2, and R3 are greater than the calculated values. What is the possible malfunction?
R4 is shorted.
The fourth resistor is open.
Resistor R1, R2, or R3 is open.
R1, R2, or R3 is shorted.
None of these.
The voltage divider circuit board, as shown below, does not provide the specified voltages: 24 V at pin 3 and pin 4, all other pins have 0V. The voltages specified with respect to the negative terminal of the power supply are given:
Pin 1: negative terminal of the 24 V power supply
Pin 2: 5.4 V ± 5 %
Pin 3: positive terminal of the 24 V power supply
Pin 4: 20.8 V ± 5 %
Pin 5: 16.0 V ± 5 %
Pin 6: 14.6 V ± 5 %
Pin 7: 12.0 V ± 5 %
The circuit does not provide the specified voltages. Identify the likely fault for the following case: 24 V at pins 3 and 4. All other pins have 0 V.
There is an open circuit between pin 4 and pin 5 (R5 open).
There is a solder splash between pin 4 and pin 5.
There is a cable break between pin 1 and the negative terminal of the 24 V power supply
There is a solder splash between pin 6 and pin 7
There is an open circuit between R5 and R6.
The circuit below shows a basic panel illumination circuit schematic. Which of the following statements about the functionality of the panel illumination circuit, as shown below, are correct? Two Answers are correct.
The fuse is for circuit protection in case of a short circuit
The brightness of the lamp is proportional to the amount of current through the lamp
The brightness of the lamp is proportional to the resistance value of the potentiometer
If the moving contact (wiper arm) of the potentiometer is disconnected from its resistive element, the amount of light on the instrument is at its maximum.
In the case of a cable break between switch and potentiometer, the fuse should be blown
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.
When the needle of an analog ohmmeter indicates infinity, the resistor being measured is:
Shorted
Open
Reversed
Overheated
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.
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
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
A 24 V DC contactor controls a 3-phase AC motor (230V/400V). Which of the following measurements are correct? Two answers are correct
Contactor activated: 400 V between terminal 1 and 4.
Contactor activated: 400 V between terminals 1 and 6 - 400 V.
Contactor not activated: 400V between terminal 33 and earth.
Contactor not activated: 0V between terminals 3 and 5.
Contactor activated: 230V between terminals 1 and 2.
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
A Wheatstone bridge is used in a temperature-sensing application. The temperature of a liquid in an industrial process is monitored using a thermistor in one branch of the bridge, as shown below. From the graph of thermistor resistance versus temperature, the calculated resistance value to which the potentiometer R2 must be set in order to balance the bridge at 60°C is:
4.4 kΩ
5.6 kΩ
6.8 kΩ
8.2 kΩ
3.3 kΩ
The figure below shows a graph of current as a function of voltage for three resistance values. Determine R1, R2, and R3.
R1: 1.0 Ω R2: 4.7 Ω R3: 3.3 Ω
R1: 4.7 Ω R2: 2.2 Ω R3: 1.0 Ω
R1: 1.0 Ω R2: 2.2 Ω R3: 4.7 Ω
R1: 4.7 Ω R2: 2.2 Ω R3: 3.3 Ω
R1: 1 MΩ R2: 2.2 Ω R3: 4.7 Ω
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.
There are metal work pieces on a circular conveyor belt. The position of the work piece carrier is detected by a switch that is magnetically sensitive. The block diagram of the sensor is
C
D
E
B
A
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
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.
Which of the following statements about the circuit shown below are correct? Two answers are correct
Neither the positive nor the negative terminal of the single source Vs is connected to ground.
The circuit produces both positive and negative voltages from a single source Vs.
The voltages at points B and C are positive with respect to ground.
The voltage at point C is positive with respect to ground.
The voltage at point B is negative with respect to ground.
By reading the multimeters in the electrical circuit shown below, determine the type of failure in the circuit and which component failed.
There is a solder splash short circuit between point A and point B.
R2 is shorted.
R1 is shorted.
R4 and R5 are open.
R3 is shorted.
