Nursing Elites

1. A box is moved by a 15 N force over a distance of 3 m. What is the amount of work that has been done?

• A. 5 W
• B. 5 N⋅m
• C. 45 W
• D. 45 N⋅m

Correct answer: D

Rationale: Work done is calculated using the formula: Work = Force x Distance. In this case, the force applied is 15 N and the distance covered is 3 m. Thus, work done = 15 N x 3 m = 45 N⋅m. Therefore, the correct answer is 45 N⋅m. Choice A (5 W) is incorrect because work is measured in joules (J) or newton-meters (N⋅m), not in watts (W). Choice B (5 N⋅m) is incorrect as it miscalculates the work by not multiplying the force by the distance. Choice C (45 W) is incorrect because work is not measured in watts (W) but in newton-meters (N⋅m).

2. When two identical charged spheres, both positively charged, are brought close together, the electrostatic force between them will be:

• A. Slightly attractive
• B. Zero
• C. Strongly attractive
• D. Strongly repulsive

Correct answer: D

Rationale: When two positively charged spheres are brought close together, they will experience a repulsive force due to their like charges. The electrostatic force causes the spheres to repel each other, making the correct answer D: Strongly repulsive. The force is not dependent on the material of the spheres, and the force is definitely not zero, as like charges repel. Choice A is incorrect as like charges do not attract each other. Choice C is incorrect as like charges repel, not attract.

3. A solenoid is a long, tightly wound coil of wire that acts like a bar magnet when current flows through it. The magnetic field lines inside a solenoid are most similar to the field lines around:

• A. A single straight current-carrying wire
• B. A horseshoe magnet
• C. A permanent bar magnet
• D. A flat sheet conductor

Correct answer: C

Rationale: The magnetic field lines inside a solenoid resemble the field lines around a permanent bar magnet. Both a solenoid and a bar magnet have north and south poles, resulting in a similar pattern of magnetic field lines. A single straight current-carrying wire produces a different field pattern because it has no coil structure like a solenoid. A horseshoe magnet has a unique field shape due to its pole arrangement, different from the uniform field pattern of a solenoid. A flat sheet conductor does not exhibit the same magnetic field characteristics as a solenoid, as it lacks the coil shape and alignment of a solenoid's magnetic field.

4. A 120-volt heat lamp draws 25 amps of current. What is the lamp’s resistance?

• A. 96 ohms
• B. 104 ohms
• C. 150 ohms
• D. 4.8 ohms

Correct answer: D

Rationale: To find the resistance of the lamp, we use Ohm’s Law, which states that resistance (R) is equal to voltage (V) divided by current (I), expressed as: R = V / I. Given that the voltage (V) is 120 volts and the current (I) is 25 amps, we substitute these values into the formula: R = 120 V / 25 A = 4.8 ohms. Therefore, the resistance of the lamp is 4.8 ohms. Choice A, 96 ohms, is incorrect as it is not the result of the correct calculation. Choice B, 104 ohms, is incorrect as it does not match the calculated resistance. Choice C, 150 ohms, is incorrect as it is not the correct resistance value obtained through the calculation.

5. Which conclusion can be drawn from Ohm’s law?

• A. Voltage and current are inversely proportional when resistance is constant.
• B. The ratio of the potential difference between the ends of a conductor to current is a constant, R.
• C. Voltage is the amount of charge that passes through a point per second.
• D. Power (P) can be calculated by multiplying current (I) by voltage (V).

Correct answer: B

Rationale: Ohm's law states that the ratio of the potential difference (voltage) between the ends of a conductor to the current flowing through it is a constant. Mathematically, this is represented as V = I x R, where V is voltage, I is current, and R is the constant resistance. Therefore, the correct conclusion that can be drawn from Ohm's law is that the ratio of the potential difference between the ends of a conductor to current is a constant, denoted as R. This relationship is fundamental to understanding the behavior of electrical circuits and the effect of resistance on voltage and current. Choice A is incorrect because Ohm's law actually states that voltage and current are directly proportional when resistance is constant. Choice C is incorrect because voltage is not the amount of charge that passes through a point per second; rather, it is the electric potential energy per unit charge. Choice D is incorrect because although power (P) can be calculated by multiplying current (I) by voltage (V), this is not a conclusion directly drawn from Ohm's law.

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