Nursing Elites

1. 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.

2. The specific heat capacity of water is about 2 J/g°C. How much energy would you need to heat 1 kilogram of water by 10°C?

• A. 420 J
• B. 4,200 J
• C. 42,000 J
• D. 420,000 J

Correct answer: C

Rationale: The formula to calculate the energy required to heat a substance is Q = m × c × ΔT, where m is the mass, c is the specific heat capacity, and ΔT is the change in temperature. Given that 1 kilogram of water is equal to 1,000 grams, the mass (m) is 1,000 g, the specific heat capacity (c) of water is 4.2 J/g°C (not 2 J/g°C), and the change in temperature (ΔT) is 10°C. Substituting these values into the formula: Q = 1,000 × 4.2 × 10 = 42,000 J. Therefore, the correct energy required to heat 1 kilogram of water by 10°C is 42,000 J. Choices A, B, and D are incorrect as they do not consider the correct specific heat capacity of water or the conversion of mass to grams.

3. What force was applied to the object that was moved if 100 Nâ‹…m of work is done over 20 m?

• A. 5 N
• B. 80 N
• C. 120 N
• D. 2,000 N

Correct answer: A

Rationale: Work is calculated using the formula Work = Force x Distance. Given that 100 Nâ‹…m of work is done over 20 m, we can rearrange the formula to solve for Force. Force = Work / Distance. Plugging in the values, we get Force = 100 Nâ‹…m / 20 m = 5 N. Therefore, the force applied to the object that was moved is 5 N. Choice B (80 N) is incorrect because it doesn't match the calculated force of 5 N. Choice C (120 N) is incorrect as it is higher than the calculated force. Choice D (2,000 N) is incorrect as it is significantly higher than the correct force of 5 N.

4. According to Bernoulli's principle, when the flow velocity (v) of an incompressible fluid increases in a constricted pipe, the pressure (P) will:

• A. Depend on the specific fluid type
• B. Decrease
• C. Remain constant
• D. Increase

Correct answer: B

Rationale: Bernoulli's principle states that in a constricted pipe with increasing flow velocity of an incompressible fluid, the pressure decreases. This is due to the conservation of energy, where the total energy of the fluid (sum of kinetic energy, potential energy, and pressure energy) remains constant along the flow path. As the fluid velocity increases, its kinetic energy increases at the expense of pressure energy, causing a decrease in pressure. Therefore, the correct answer is B. Choices A, C, and D are incorrect. The pressure changes in the system are primarily driven by the fluid velocity and the conservation of energy principle, not by the specific fluid type, which is a constant. The pressure is not constant but decreases with increasing flow velocity due to the energy transformation occurring in the system. Lastly, the pressure does not increase; it decreases as the fluid velocity rises.

5. The operating principle of a metal detector relies on:

• A. The static presence of a permanent magnet
• B. The electromotive force induced by a changing magnetic field
• C. The high electrical conductivity of most metals
• D. The unique thermal signature of metallic objects

Correct answer: B

Rationale: The correct answer is B. Metal detectors work based on the principle of electromotive force induced by a changing magnetic field. When a metal object comes into contact with the detector's magnetic field, it disrupts the field, inducing a current in the metal that can be detected. This principle allows metal detectors to identify the presence of metallic objects without relying on the static presence of a permanent magnet, the high electrical conductivity of metals, or the thermal signature of the objects. Choice A is incorrect because metal detectors do not rely on a static magnet but on the interaction of metals with a changing magnetic field. Choice C is incorrect because while metals do have high electrical conductivity, this is not the principle underlying metal detectors. Choice D is incorrect because metal detectors do not operate based on the thermal signature of objects, but rather on their interaction with magnetic fields.

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