E3AP - EE 01-02 | Take the Quiz

Which of the following statements is FALSE about the operation of parallel shunt generators?

The parallel configuration makes it possible to add units as needed, and to shut off unnecessary units at low load demands.

One large unit would be more expensive than he uses of several smaller ones, even if it ran at full load at all times.

The doping load or decreasing terminal voltage characteristic of shunt generators makes two or more units operating in parallel more stable.

The use of several units makes maintenance and repair easier.

In a DC motor, what is the definition of field resistance?

It is the resistance of the excitation circuit.

It is the load resistance seen by a generator without considering inductance.

It is the resistance of the armature windings plus the load resistance,

It it the static resistance of the motor.

The material used for fuse wire must have

High melting point and low specific resistance

Low melting point and low specific resistance

Low melting point with any specific resistance

Low melting point and high specific resistance

An electron traveling north enters a region where the electric field is uniform and points west. The electron:

Slows down

Veers east

Speeds up

Veers west

Helmholtz coils are commonly used in the laboratory because the magnetic field between them:

Is especially strong

Can be varied more easily than the fields of other current arrangements

Is nearly uniform

Is parallel to the plane of the coils

A dielectric slab is slowly inserted between the plates of a parallel plate capacitor, while the potential difference between the plates is held constant by a battery. As it is being inserted:

The capacitance, the potential difference between the plates, and the charge on the positive plate all increase

The capacitance and the charge on the positive plate decrease but the potential difference between the plates remains the same

The capacitance and the charge on the positive plate increase but the potential difference between the plates remains the same

The potential difference between the plates increases, the charge on the positive plate decreases, and the capacitance remains the same

A transmission line has a reactance of 1 Pu is operating at Vs = Vr = 1 Pu. The generator is connected at source end which is delivering 0.5 Pu of active power. Find the load angle?

30°

35°

45°

60°

You wish to triple the rate of energy dissipation in a heating device. To do this you could triple:

The potential difference keeping the resistance the same

The current keeping the resistance the same

The resistance keeping the potential difference the same

The resistance keeping the current the same

Which of the following statements regarding transformers is FALSE?

One-three phase transformer weighs more than three equivalent single-phase transformers.

The copper losses (I2R) in the primary and secondary coils are equal

Transformer power losses are generally low, approximately 1-3%

Power losses in transformers are converted to heat, which is then dissipated

Two conducting spheres are far apart. Smaller sphere carries a total charge Q. The larger sphere has a radius that is twice that of the smaller and is neutral. After the two spheres are connected by a conducting wire, the charges on the smaller and larger spheres, respectively, are:

Q/2 and Q/2

2Q/3 and Q /3

Q/3 and 2Q/3

2Q and -Q

Two capacitors are identical except that one is filled with air and the other is filled with oil. Both capacitors carry the same charge. If Eair refers to the electric field inside the capacitor filled with air and Eoil refers to the electric field inside the capacitor filled with oil then the ratio of the electric fields Eair/Eoil will be

Between 0 and 1

Between 1 and infinity

For 800 MJ stored energy in the rotor at synchronous speed, what is the inertia constant H for a 50 Hz, four pole turbo generator rated 100 MVA, 11 kV?

2 MJ/MVA

4 MJ/MVA

6 MJ/MVA

8 MJ/MVA

E3AP - EE 01-02

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