M3AM

Why are the valence electrons important?. Because they influence the surrounding atoms. Because they identify positive or negative atoms. Because they are the majority.

Which is the typical valence of an semiconductor?. 5 or higher. 3 or lower. 4.

How atoms spontaneously tend to reach stability?. Keeping the most external shell complete. Decreasing the number of electrons. With a radioactive decay.

Which is the main characteristic of an AC induction motor?. Its rotor is supplied by direct current. Its rotor is not supplied by any type of voltage source. Its rotor is supplied by alternating current.

Which of these is a characteristic of a resistor start motor?. The main winding has a high resistance. The main winding has a large angle. The main winding has a high inductance.

Which kind of synchronous motors configurations are possible?. Only single phase. Only multi-phase (three-phase). Single and multi-phase Correct.

What is the rotor?. The mobile part of a generator. It is the fixed part of the generator. The part of a generator that produces the magnetic field.

In an alternator, what is the armature?. The part of the generator that produces the magnetic field. The part of the generator where the electromotive force is induced. It is the fixed part of the generator.

How is it called the part that generates the magnetic field in a generator?. Field. Magnet. Armature.

Where is located the armature circuit in a rotating field alternator?. It is fixed and it is located on the stator part of the generator. It is fixed and it is located on the inductor part of the generator. It is fixed and it is located on the rotor part of the generator.

How is possible to create a low-pass filter?. With a capacitor in series with the load. With a resistor in series with the load. With an inductor in series with the load.

Let’s think of a transformer with a 3 to 5 ratio, connected to a 30V and 15A input circuit. Which is the value of the power of the input circuit?. 400W. 350W. 450W.

A transformer is a device able to modify: Work. Voltage. Power.

How many windings does a three-phase transformer have?. Six. Nine. Three.

How many windings does a single-phase transformer have?. Two. Three. One.

What happens in a RCL circuit in parallel?. The voltage is the same in all the branches of the circuit. The current is the same in all the branches of the circuit. Voltage and current are different in all the branches of the circuit.

What does the inductive reactance depend on?. It depends on voltage frequency and on inductor inductance. It depends on voltage frequency and on current intensity on inductors. It depends on current intensity and on inductor inductance.

What does capacitive reactance depend on?. Inductance. Voltage level. Capacitor capacity.

What is a parallel RCL circuit?. A circuit where inductors or capacitors are in series. A circuit where inductors or capacitors are in parallel. A circuit with capacitors and inductors both in series and in parallel.

Why are three-phase waves more used than single-phase wave?. Because they use less electric power. Because they use small wires and cover more distance. Because they are easier to transform into direct current.

Which of these is the RMS value for a triangular waveform?. Vp/√2. Vp/√3. Vp/2.

What is the form factor?. It is the ratio between maximum value and RMS. It is the ratio between average value and RMS. It is the ratio between RMS and average value.

What is the average of a triangular ware after half cycle?. Its minimum value. Its maximum value. Half of its maximum value.

Which of the following instruments regulates fluctuations in a three-stage system generator?. A Vibrating voltage regulator. A current limiter. A reverse current relay.

In a generator, the conductor with the shape of a coil is placed inside a: Magnetic field. Electromagnetic field. Electric field.

How are usually generators moved in the aeronautical field?. By an electric engine. By an asynchronous engine. By the aircraft engines.

What does a conductor moved inside a magnetic field produce?. An alternate current. A potential difference. A direct current.

What happens to the Coulomb force if we change the medium between the two charges doubles?. The force becomes half. It depends on the medium. The force double.

Which is the measurement unit of the quantity of charge?. T, Tesla. C, Coulomb. F, Farad.

Which of these factors affect Coulomb's force?. The forces produced by the existing magnetic field between the two magnets depend on the magbitude of charges and temperature. The forces produced by the existing magnetic field between the two magnets depend on the magbitude of charges and gravity. The forces produced by the existing magnetic field between the two magnets depend on the distance between the two magnets and on the quantity of charges.

How can the electrical field be graphically represented?. through a scalar product scheme. through Bernoulli's scheme. through Faraday's scheme.

Which is the unit of measurement of the Conductance?. Farad. Siemens. Volt.

Which is the measurement unit of Conductance?. S, Siemens. C, Coulomb. V, Volt.

Which letter is used to indicate the conductance?. C. S. G.

How can be used the principle of electromagnetic induction?. To transform mechanical energy into electric energy. To transform kinetic energy into electric energy. To transform chemical energy into electric energy.

Where electric current is generated by heat?. In the thermocouples. In the generator. In the turbine.

Which is the nature of light?. Corpuscular. Both undulating and corpuscular. Undulating.

How are thermocouples connected?. Some in series and some in parallel. In parallel. In series.

How can I decrease the internal resistance of a battery?. Increasing the number of cells. Connecting more cells in series. Connecting more cells in parallel.

What is the reference temperature in the thermocouple?. The certified temperature. Temperature of the hot junction. Temperature of the cold junction.

When the conductors that connect the junction box to the indication system are made of the same material as thermocouples, how are they called?. Ex-voltage conductors. Compensation conductors. Thermocouple conductors.

What is the relation between Voltage and Resistance?. Directly proportional. Inversely proportional. Exponentially proportional.

Which is the correct statement for the Kirchhoff's voltage law?. In a closed mesh the sum of the electro-motive forces must be equal to the sum of the voltage drops across the loads. The algebraic sum of the drops in a closed mesh must be null. The algebraic sum of the electro-motive force in a closed mesh must be null.

What is the relation between Voltage and Current?. Inversely proportional. Exponentially proportional. Directly proportional.

Which is the formula for the conductor's resistance ?. R = ρ / (l x A). R = (ρ x l) / A. R = ρ x l x A.

Which is the unit of measurement of the resistivity?. Ohm. Siemens/meter. Ohm*meter.

Which is the SI unit of the resistivity ?. Watt (W). ohm Ω. ohm meter Ωm.

Why is conductance useful?. It is important when we have to find the total resistance of a series connection. It is important when we have to find the total resistance of a parallel connection. It is important for measures.

Which is another common measurement unit for power ?. Newton. Dina. Horse power.

Which formula is used to compute the power P of a circuit? (R resistance, i current intensity). P = R(i)³. P = R x i. P = R (i)².

How may power be defined ?. Power is the force per unit area applied in a direction perpendicular to the surface of an object. Power is a physical parameter that measures the quantity of work performed within a certain time. Power is the ability of a physical system to produce changes on another physical system.

What is electrical power?. It is quantity of work performed divided the time. It is the quantity of energy used divided the time. It is the quantity of work multiplied for the time.