ELECTRICITY AND MAGNETISM TEST QUESTIONS (FOR G-10)

Direction: Choose the letter of the correct answer.

1.  In which case or cases is electric field present?

I.  A spark jumping between two nearby rods.

II.  A charge that is momentarily at rest.

III.  A rotating bar magnet.

a.  I only

b.  I and II only

c.  II and III only

d.  I, II and III

2.  In which case can a magnetic field be produced?

a.  A charged comb.

b.  A falling glass rod.

c.  A welder’s arc flash.

d.  A rolling plastic cylinder.

3. Which device can be used to determine the polarity of an unmarked magnet?

a.  a charged glass stirring rod

b.  a gold-leaf electroscope

c.  a sprinkle of iron filings

d.  an improvised compass

4. How will you describe the magnetic field around a straight current-carrying wire?

a.  The magnetic field is strongest near and around the wire.

b.  The magnetic field consists of straight lines parallel to the wire.

c.  The magnetic field does not vary with the distance from the wire.

d.  The magnetic field gets stronger with increasing distance from the wire.

5. Which statement about an electromagnet is TRUE?

a.  The electric field surrounding a battery-powered electromagnet  alternates constantly.

b.  The current in the electromagnet coil temporarily magnetizes the iron core.

c.  The electric field strength is inversely proportional to the current.

d.  The magnetic field lines produced are all straight.

6. What can be inferred from the alignment of compass needles in the set-up below?

a. A permanent magnet is nearby.

b. The power switch was turned off for long.

c. The current-carrying coil becomes magnetic.

d. There is a constant and uniform magnetic field around the coil.

7. As part of a traffic light system, large loops of wire are buried beneath road intersections. Which of the statements is NOT TRUE about the operation of this traffic light system?

a.  Vehicles driven over the buried coils activate a traffic light sensor.

b.  The conducting loops activate a color–dependent field.

c.  The alternating current sent through the buried coils produce an electromagnetic field in each coil.

d.  A minimum number of vehicles over the coils can trigger the traffic light to change green.

8. Complete the following statement: Moving a metallic detector past a 5 peso coin creates a secondary magnetic field that is most similar to that of __.

a.  a horse shoe magnet

b.  a flat refrigerator magnet

c.  a current-carrying, circular loop

d.  a V-shaped straight wire that carries a current

9. During the Student Technologists and Entrepreneurs of the Philippines (STEP) Competition in Landscaping, a water pond transformer changes 216V across the primary to 12 V across the secondary. If the secondary coil has 10 turns, how many turns does the primary coil have?

a.  10 turns

b.  18 turns

c.  180 turns

d.  228 turns

10. What basic principle enables ALL electric motors to operate?

a.  Iron is the only element that is magnetic.

b.  Opposite electric charges attract and like charges repel.

c.  A  moving  conductor  within  a  magnetic  field  will  experience  an electromotive force.

d.  A current-carrying conductor placed within a magnetic field will experience a magnetic force.

11. A magnet moves inside a coil. Consider the following factors:

I. strength of the magnet

II. number of turns in the coil

III. speed at which the magnet moves

     Which can affect the electromotive force (emf) induced in the coil?

a.  I only

b.  II only

c.  III only

d.  All three factors

12. Which statement about transformers is FALSE?

a.  A step-down voltage transformer steps up the current.

b.  Transformers use mutual induction.

c.  Transformers are an application of Faraday’s and Lenz’s Laws.

d.  A transformer can function with either an alternating current (AC) or a steady direct current (DC).

13. What is TRUE about the intercom system that is shown below?

a.  The part A of the intercom system serves as a microphone only, while part C serves as a loudspeaker only.

b.  Either parts A and C of the intercom when switched as such can be used as a microphone or as a loudspeaker.

c.  The microphone part only basically consists of wires, a cone diaphragm, a magnet, and a coil.

d.  The loudspeaker part only basically consists of wires, a cone diaphragm, a magnet, and a coil.

14. What transformation can take place in an improvised generator?

a.  mechanical energy into electrical energy

b.  electrical energy into mechanical energy

c.  alternating current into direct current

d.  direct current into alternating current

15. A loop of conductor lies flat on a horizontal table. A toy magnet is hanging still over  it  with  the  magnet’s  north-seeking  pole  pointing  down.  What happens next?

a.  The magnet produces a clockwise current in the coil.

b.  The magnet does not produce any current in the coil.

c.  The magnet produces an upward electromagnetic current.

d.  The magnet produces a counterclockwise current in the coil.

16. Which arrangement of three bar magnets results to an attraction between the first and the second, and a repulsion between the second and the third magnet.

17. Which set ups model the working principle of a transformer and an electric generator respectively?

a. A and B         b. B and D             c. C and D              d. D and A

18. Which statement is TRUE about the illustration below?

a.  In set up A, the magnet is at rest inside the moving coil.

b.  In set up B, the magnet is being pulled out of the moving coil with the same speed.

c.  There is relative motion between the magnet and coil in set up A.

d.  There is relative motion between the magnet and coil in set up B.

19.  What is TRUE about the intercom system that is shown below?

a.  The part A of the intercom system serves as a microphone only, while part C serves as a loudspeaker only.

b.  Either parts A and C of the intercom when switched as such can be used as a microphone or as a loudspeaker.

c.  The microphone part only basically consists of wires, a cone diaphragm, a magnet, and a coil. 

d.  The loudspeaker part only basically consists of wires, a cone diaphragm, a magnet, and a coil.

20. What transformation can take place in a ceiling fan’s electric motor?

a.  electrical energy into mechanical energy

b.  mechanical energy into electrical energy

c.  alternating current into direct current

d.  direct current into alternating current


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