AC Generators

Which of these is NOT a part of a DC Generator.

• Slip rings
• commutator 
• brushes
• stator

Which is the device in DC Generators that converts AC current into DC current

• brushes
• commutator 
• stator
• armature

The process of generating the current in a conductor is called as 

• Electro motive force 
• Electromagnetic induction 
• generator energy conversion 
• induced voltage

AC generators have 

• 2 slip rings 
• 1 slip ring 
• 3 slip rings 
• 4 slip rings

Which ONE of the following actions will NOT cause an increase in the induced emf in a coil if the coil is rotated in a uniform magnetic field?

• Rotating the coil faster

• Increasing the strength of the magnetic field

• Increasing the number of turns of the coil

• Replacing the coil with a coil of lower resistance

Some learners decided to build a small electrical generator in the laboratory. They then used this generator to investigate how the magnitude of the induced emf would change as the magnetic field strength changed.

Which ONE of the following is CORRECT regarding the variables for the investigation?

• DEPENDENT VARIABLE: Magnitude of induced emf

  INDEPENDENT VARIABLE: Number of turns of coil of generator

  CONTROL VARIABLE: Magnetic field strength

• DEPENDENT VARIABLE: Number of turns of coil of generator

  INDEPENDENT VARIABLE: Magnitude of induced emf

  CONTROL VARIABLE: Magnetic field strength

• DEPENDENT VARIABLE: Magnitude of induced emf

  INDEPENDENT VARIABLE: Magnetic field strength

  CONTROL VARIABLE: Number of turns of coil of generator

• DEPENDENT VARIABLE: Magnetic field strength

  INDEPENDENT VARIABLE: Number of turns of coil of generator

  CONTROL VARIABLE: Magnitude of induced emf

Which ONE of the following changes may lead to an increase in the emf of an AC generator without changing its frequency?

• Decrease the resistance of the coil.

• Increase the area of the coil.

• Increase the resistance of the coil.

• Decrease the speed of rotation.

The speed of rotation of the coils in an AC generator is increased. Which ONE of the following combinations of frequency and output voltage for the generator will occur as a result of the change?

• FREQUENCY: Increases

  OUTPUT VOLTAGE: Increases

• FREQUENCY: No change

  OUTPUT VOLTAGE: Increase

• FREQUENCY: Decrease

  OUTPUT VOLTAGE: Decrease

• FREQUENCY: Increase

  OUTPUT VOLTAGE: No change

Graph P represents the output emf of an AC generator. Graph Q is the output emf after a change has been made using the same generator. Which one of the following changes has been made to the generator to produce graph Q?

• The number of turns of the coil has been doubled

• The surface area of the coil has been doubled

• The speed of rotation has been doubled

• The strength of the magnetic field has been doubled

The voltage induced in a conductor is ___________ ___________ to the rate which the conductor cuts the magnetic lines of force.

• inversely proportional

• directly proportional

• negatively coorelated

• absolutely opposite