household alternating current typically has a frequency of 60 hz which statement is true

HESI A2

HESI A2 Physics Practice Test

1. Household alternating current typically has a frequency of 60 Hz. Which statement is true?

A. The circuit is suitable for lighting 60-watt bulbs.
B. Circuits in the home may carry a current of 60 amperes.
C. The expected voltage drop is 60 volts per meter.
D. Electrons complete a cycle 60 times per second.

Correct answer: D

Rationale: The correct answer is D. Electrons complete a cycle 60 times per second when the frequency of the current is 60 Hz. This frequency indicates that the current changes direction 60 times per second, causing the electrons to complete a full cycle back and forth through the circuit at the same rate. Choice A is incorrect because the power rating of a bulb (in watts) is not directly related to the frequency of the current. Choice B is incorrect as typical household circuits do not carry currents as high as 60 amperes. Choice C is incorrect as the expected voltage drop is not measured in volts per meter for household alternating current circuits.

2. What is the electric field inside a hollow conductor with a net charge?

A. Remains constant
B. Decreases
C. Zero
D. Becomes unpredictable

Correct answer: C

Rationale: The correct answer is C: Zero. According to Gauss’s Law, the electric field inside a hollow conductor (a conductor with no charge inside but a net charge on its surface) is zero. The charges reside on the outer surface of the conductor, causing the electric field inside to cancel out. Choices A, B, and D are incorrect because the electric field inside a hollow conductor with a net charge is not constant, does not decrease, and does not become unpredictable; it is zero due to the distribution of charges on its surface.

3. When calculating an object’s acceleration, what must you do?

A. Divide the change in time by the velocity.
B. Multiply the velocity by the time.
C. Find the difference between the time and velocity.
D. Divide the change in velocity by the change in time.

Correct answer: D

Rationale: When calculating an object's acceleration, you must divide the change in velocity by the change in time. Acceleration is defined as the rate of change of velocity with respect to time. By determining the ratio of the change in velocity to the change in time, you can ascertain how quickly the velocity of an object is changing, thereby finding its acceleration. Choice A is incorrect because acceleration is not calculated by dividing time by velocity. Choice B is incorrect as it describes multiplying velocity by time, which does not yield acceleration. Choice C is incorrect as finding the difference between time and velocity is not a method to calculate acceleration.

4. Bernoulli's principle for an incompressible, inviscid fluid in steady flow states that the mechanical energy, consisting of:

A. Pressure (P) only, remains constant along a streamline.
B. Velocity (v) only, remains constant along a streamline.
C. P + ½ρv² (total mechanical energy), remains constant along a streamline
D. Density (ρ) only, remains constant along a streamline.

Correct answer: C

Rationale: Bernoulli's principle states that the sum of pressure energy (P), kinetic energy per unit volume (½ρv²), and potential energy per unit volume remains constant along a streamline in an incompressible, inviscid fluid. This means the total mechanical energy of the fluid is conserved, making Choice C the correct answer. Choices A, B, and D are incorrect because Bernoulli's principle involves the conservation of the total mechanical energy, not just pressure, velocity, or density alone.

5. In a U-tube manometer, a fluid is used to measure pressure differences. When one side is connected to a pressurized system, the fluid level on that side will:

A. Remain the same
B. Decrease
C. Increase
D. Depend on the type of fluid used

Correct answer: B

Rationale: In a U-tube manometer, the side connected to a pressurized system will experience a decrease in fluid level due to the pressure exerted by the system. This pressure forces the fluid down, causing the fluid level to decrease. Therefore, choice B is correct. Choices A and C are incorrect because the fluid level will not remain the same or increase when connected to a pressurized system. Choice D is incorrect as the type of fluid used does not determine the direction of the fluid movement in response to pressure.