Simple Electric Motor and Generator

What device is made of coils of wire with an electrical current passing through it in order to generate a magnetic field?  

• Electromagnet

• Electron magnet

• Generator

• Motor

To increase the magnifying power of a telescope, the focal length of ______.

• Objective lens should be increased.

• Objective lens should be decreased.

• Eye-piece lens should be increased.

• Eye-piece lens should be decreased.

In an electric motor, the energy transformation begins as ---------.

• electrical and becomes chemical

• electrical and becomes mechanical

• mechanical and becomes electrical

• mechanical and becomes chemical

Which of the following optical instruments will be used to produce a reduced and inverted image of distant objects?

• camera

• microscope

• projector

• refracting telescope

In projectors which lenses are used?

• Convex lens

• Concave lens

• Bipolar lens

• Both A and B

Electric motors are significant in industries which is also used in a variety of applications. Which of the following devices does NOT apply the working principle of an electric motor?

• Drills

• Water pumps

• light bulb

• Washing machine

Electromagnetic induction was discovered by

• Thomas Edison

• Nikola Tesla

• Benjamin Franklin

• Michael Faraday

To correct nearsightedness, a person is prescribed with what kind of lenses?

• Converging lens

• Diverging lens

• Focusing lens

• None of the above.

Which is the correct sequence in the operation of simple motor?

 I. Magnets placed near one another either attract or repel.

 II. The attraction and repulsion causes the wire to jump.

 III. Electric current starts to creep along wire; it creates a magnetic field all around it.

 IV. Electrical energy converted to mechanical energy. 

V. Temporary magnetic field interacts with the permanent magnet

• V, IV, II, II, I

• III, V, I, II, IV

• V, III, I, IV, III

• III, II, IV, I, V

What are the three basic parts of an electric motor?

• commutator, stator, and rotor

• armature, brushes, and battery

• commutator, armature, and brushes

• battery, armature, and DC power supply