EE COACHING SET 1

Nine identical wires, each of diameter d and length L, are connected in series. The combination has the same resistance as a single similar wire of length L but whose diameter is: 

• 9d

• d/3

• 3d

• d/9

 

If a tropical storm is going to the Philippine Area of Responsibility (PAR) within 24 hours what type of alert is to be raised in accordance to the Philippine Grid Code?

• Blue Alert

• Orange Alert

• Red Alert

• Yellow Alert

Three single-phase transformers rated 25 kVA each are connected in delta-delta to supply a balanced load of 75 kVA. One transformer is removed for repair, what is the kVA of each remaining transformer?

• 43.3

• 34.3

• 57.7

• 50

A charged capacitor and an inductor are connected in series. At time t = 0 the current is zero, but the capacitor is charged. If T is the period of the resulting oscillations, the next time after t = 0 that the energy stored in the electric field of the capacitor is a maximum is:

• T /2

• 2 T

• T / 4

• T

 As a loop of wire with a resistance of 10 Ω moves in a constant non-uniform magnetic field, it loses kinetic energy at a uniform rate of 4.0 mJ/s. The induced current in the loop:

• 30 mA

• 20 mA

• 10 mA

• cannot be calculated from the given data

What is the equivalent of 1 + a + a^2?

• 0

• -1

• 1 + j

• 1

What is the maximum speed at which a 60 Hz synchronous machine can be operated?

• 3600 rpm

• 3200 rpm

• 3400 rpm

• 3000 rpm

The magnetic field B inside a long ideal solenoid is independent of: 

• the spacing of the windings

• the cross-sectional area of the solenoid

  
  

• the core material

• the current

 

1 weber is the same as:

• 1 V · s

• 1 T/m

• 1 T · s

• 1 V/s

The terminal voltage of a battery is 11.8 V when delivering 20 W of power to an external load resistor R. If the battery has an emf of 15 V, find the internal resistance of the battery.

• 1.75 ohm

• 1.96 ohm

• 1.68 ohm

• 1.89 ohm