lopez

The SI unit of flux density is

• Gauss

• Weber

• Maxwell

• Tesla

Calculate the flux density a magnetic flux of 500Mx through an area of 10cm2

• 0.05 Oe

• 5 Gb

• 50 G

• 0.5 T

Which of the following statements accurately describes the characteristics of an electromagnet?
1. Increasing the number of coils turned enhances the magnetic field's strength.
2. Reducing the current and decreasing the coil turns results in a stronger magnetic field.
3. Absence of current in the coil means there is no magnetic field.

• Statements 1 and 3 are correct.

• Statement 1 is correct.

• Statement 2 is correct.

• Statement 3 is correct.

The ability of a material to concentrate magnetic flux is called its

• Hall Effect

• Permeability

• Induction

• Diamagnetic

Multiple choice (one answer) A magnet that require current in a coil to create magnetic field is called a/an

• electromagnet

• magnetron

• the earth itself

• permanent magnet

A 100V d.c. generator supplies a current of 15A when running at 1500rev/min. If the torque on the shaft driving the generator is 12Nm. Determine the total power loss

• 1135 W

• 385W
  

• 835 W
  

• 2270W

A 100V d.c. generator supplies a current of 15A when running at 1500rev/min. If the torque on the shaft driving the generator is 12Nm. Determine the generated emf.

• 106.34

• 134.26

• 98. 64

• 125.65

A 100V d.c. generator supplies a current of 15A when running at 1500rev/min. If the torque on the shaft driving the generator is 12Nm. Determine the armature resistance

• 0.71 Ω

• 1.71Ω

• 0. 85 Ω

• 1.42 Ω

A 5kW shunt generator as shown having an armature circuit resistance of 2Ω and a field resistance of 100Ω, generates a terminal voltage of 250V at full load. Assuming the iron, friction and windage losses amount to 500W, determine the efficiency

• 90%

• 80%

• 70%

• 60%

A 5kW shunt generator as shown having an armature circuit resistance of 2Ω and a field resistance of 100Ω, generates a terminal voltage of 250V at full load. Assuming the iron, friction and windage losses amount to 500W, determine the current through the armature

• 5 A

• 22.5 A

• 20 A

• 2.5 A