                        NCFE 2013 Part 2
Accessed 10 June 2017
released 2013

 A B C D
21. A ray of light traveling in water enters a different medium. If the incident angle of the ray is 47°, and the angle of refraction bends toward the normal, what does this reveal about the index of refraction of the medium?
1. The index of refraction of the medium is less than the index of refraction of water.
2. The index of refraction of the medium is the same as the index of refraction of water.
3. The index of refraction of the medium is greater than the index of refraction of water.
4. The index of refraction of the medium is not comparable to the index of refraction of water.
 A B C D
22. Which best describes the different mediums in which the speed of light and sound is greatest?
1. Light travels fastest through air, while sound travels fastest through a diamond.
2. Light travels fastest through a diamond, while sound travels fastest through air.
3. Light travels fastest through water, while sound travels fastest through glass.
4. Light travels fastest through glass, while sound travels fastest through water.
 A B C D
23. A circuit has a voltage source and three identical resistors in parallel. How will removing one of the resistors affect the voltage of the circuit?
1. The voltage will stay the same because the voltage remains constant through parallel resistors.
2. The voltage will increase by a factor of 2 because the voltage constantly increases through parallel resistors.
3. The voltage will decrease by a factor of 2 because voltage is directly proportional to the number of parallel resistors a circuit contains.
4. The voltage will increase by a factor of 3 because voltage is indirectly proportional to the number of parallel resistors a circuit contains.
 A B C D
24. A circuit contains a voltage source and four resistors connected in series. If the voltage is decreased by one-half, what will happen to the current flowing through the circuit?
1. The current will decrease by one-fourth because current has an inverse relationship to the number of resistors that are in series.
2. The current will decrease by one-half because current has a direct relationship to the voltage of the circuit.
3. The current will double because current has an inverse relationship to the voltage of the circuit.
4. The current will quadruple because current has a direct relationship to the number of resistors that are in series.
 A B C D
25. A scientist used a material which allowed electrons to move easily from atom to atom. What can be assumed about the material the scientist used?
1. The material was a conductor.
2. The material was an insulator.
3. The material was a thermal insulator.
4. The material was a semiconductor.
 A B C D
26. Two spheres, Sphere I and Sphere II, are composed of different substances. Thesediagrams show the distribution of the electrons in the two spheres before and after they are placed next to a positively charged rod. Which sphere is most likely composed of glass?
1. Sphere I, because the electrons are tightly bound
2. Sphere I, because the electrons are free to move
3. Sphere II, because the electrons are free to move
4. Sphere II, because the electrons are tightly bound
 A B C D
27. What is the main advantage of using alternating current (AC) over direct current (DC) when transmitting electricity?
1. AC has fewer power surge problems than DC.
2. AC power lines need less insulation than DC power lines.
3. AC makes it easier to step voltage up or down with transformers, as compared to DC.
4. AC is not affected by the use of transformers, but the use of DC requires transformers.
 A B C D
28. The diagram below is of a circuit with a resistor. How much power does the resistor use?
1. 0.38 W
2. 4.5 W
3. 85 W
4. 380 W
 A B C D
29. This diagram displays a circuit with two resistors. If the circuit produces 40 W, how much energy does it use in 20 s?
1. 2,400 J
2. 800 J
3. 6 J
4. 2 J
 A B C D
30. A charged pith ball is placed between two fixed charges. The pith ball swings in the direction shown. What is the charge on the pith ball?
1. positive, because unlike charges attract
2. positive, because unlike charges repel
3. negative, because unlike charges attract
4. negative, because unlike charges repel
 A B C D
31. The magnitude of an electric field created by a charge of 2.5 × 10−9 C is measured at a distance of 0.04 m. How will the magnitude change if the distance is increased?
1. The magnitude will decrease, because the electric fieldâ€™s strength decreases with increased distance.
2. The magnitude will decrease, because the electric field is directed inward toward the charge.
3. The magnitude will increase, because the electric field is directed outward from the charge.
4. The magnitude will increase, because the electric fieldâ€™s strength increases with increased distance.
 A B C D
32. Two metal spheres (I and II) with charges of 1 × 10−6 C and 2 × 10−6 C, respectively, are separated by a distance. Sphere I experiences an electrostatic repulsion of 2.4 N from sphere II. What is the electrostatic repulsion force experienced by sphere II?
1. Sphere II experiences half the amount of repulsion force because it is twice as large as sphere I.
2. Sphere II experiences the same amount of repulsion force because an equal and opposite charge is needed to balance the force experienced by sphere I.
3. Sphere II experiences double the amount of repulsion force because it is twice as large as sphere I.
4. Sphere II experiences four times the amount of repulsion force because an equal and opposite charge is needed to balance the force experienced by sphere I.
 A B C D
33. A student walks across a carpeted floor and acquires a static electric charge. Why is this an example of friction?
1. Heat is transferred from the floor to the studentâ€™s feet.
2. Heat is transferred from the floor to the air under the studentâ€™s feet.
3. Resistance is produced between the studentâ€™s feet and the carpeted floor.
4. Current is produced by the studentâ€™s feet and the carpeted floor.
 A B C D
34. The electric potential at a point is 20 V. How much work is needed to bring a charge of 0.5 C from infinity to that point?
1. The work required to move the charge is equal to the electric potential at the point times the amount of charge being moved; therefore, 10 J of work is needed for this charge.
2. The work required to move the charge is equal to the electric potential at the point it is being moved to because the forces are equal and opposite; therefore, 20 J of work is needed for this charge.
3. The work required to move the charge is equal to the electric potential at the point over the amount of charge being moved; therefore, 40 J of work is needed for this charge.
4. The work required to move the charge is equal to the electric potential at the point over the square of the amount of charge being moved; therefore, 100 J of work is needed for this charge.
 A B C D
35. This figure shows the electric field around two positive charges placed near each other. According to the electric field lines, how will the charges move?
1. They will move toward each other and spin because they are unbalanced charges.
2. They will move apart and in the same direction because one charge is larger than the other.
3. They will move toward each other and collide because like charges attract each other.
4. They will move apart and in opposite directions because like charges repel each other.
 A B C D
36. A bar magnet has been cut into four pieces of equal length and width. What is the pole strength of each piece compared to the pole strength of the original bar magnet?
1. double, because the magnetic domain only depends on the width of the magnet
2. equal, because the magnetic domain is independent of the width and length of the magnet
3. one-half, because the magnetic domain only depends on the length of the magnet
4. one-fourth, because the magnetic domain depends on the length and width of the magnet
 A B C D
37. Which material will create the strongest magnetic field when a current-carrying wire is wrapped around the material?
1. a wool cloth, because wool is a thermal material
2. a rubber tube, because rubber is an insulating material
3. a glass pipe, because glass is a semi-conducting material
4. an iron core, because iron is a conductive material
 A B C D
38. Which would result in an increase in the magnetic field strength produced by an electromagnet?
1. increasing the space between the turns in the coil
2. increasing the number of turns in the coil
3. decreasing the current in the coil
4. decreasing the voltage in the coil
 A B C D
39. The primary coil of a transformer has 400 turns; the secondary coil has 1,000 turns. An alternating current is sent through the primary coil. The voltage in the primary coil has an amplitude of 17 V. Which statement best describes the voltage amplitude in the secondary coil?
1. between 0 V and 17 V, because transformer coils are insulators
2. between 17 V and 50 V, because transformer coils are conductors
3. between 0 V and 17 V, because the coils form a step-down transformer
4. between 17 V and 50 V, because the coils form a step-up transformer
 A B C D
40. A transformer triples its input voltage. If the current in the primary coil is 6 A, how does the current change as it moves through the secondary coil?
1. It decreases to 2 A because this is a step-up transformer.
2. It remains at 6 A because transformers are used to keep current constant.
3. It increases to 9 A because transformers are used to keep voltage constant.
4. It increases to 18 A because this is a step-down transformer. Additional North Carolina Exam Questions