HESI Exams Quizlet Physics

Correct Answer: B

Rationale: The correct answer is B: Permeability is preferred. High permeability in the core of an electromagnet enhances its magnetic field strength by allowing more magnetic flux to pass through, increasing the efficiency of the electromagnet. Resistivity (choice A) would hinder current flow, reducing magnetic field strength. Permittivity (choice C) is related to electric fields, not magnetic fields. Dielectric strength (choice D) is the ability of a material to withstand electric fields, not directly related to enhancing magnetic properties.

Correct Answer: A

Rationale: Conduction is the transfer of heat through a material without any movement of the material itself. In contrast, convection involves the movement of fluids to transfer heat, radiation transfers heat through electromagnetic waves, and isothermalization is not a recognized mode of heat transfer. Therefore, the correct answer is A because it does not involve the movement of material or fluid to transfer heat like convection does. Convection, radiation, and isothermalization are all modes of heat transfer, making them incorrect choices.

Correct Answer: B

Rationale: The correct answer is B because as a raindrop falls, air resistance increases, counteracting the force of gravity. Initially, gravity pulls the raindrop down, causing it to accelerate. However, as the raindrop gains speed, air resistance becomes stronger, eventually balancing out the gravitational force. This results in a constant velocity rather than acceleration. A: Gravity does pull the raindrop down, but it doesn't do so at a constant rate. The acceleration due to gravity is constant but is countered by air resistance. C: The mass of the raindrop remains constant as it falls, so its mass decreasing is not a factor in its speed. D: Objects in motion do not necessarily decelerate over distance; in the case of the raindrop, air resistance prevents further acceleration.

Correct Answer: B

Rationale: The correct answer is B (15.625 cm). To calculate the image height using mirror formula (1/f = 1/v + 1/u), first find the object distance (u) which is -20 cm (since object is placed on the same side as focal point, it is negative). Then, solve for image distance (v) by substituting u and f values. Next, use magnification formula (m = -v/u) to find the magnification factor. Finally, multiply the object height by the magnification factor to get the image height, which is 15.625 cm. Choice A (30.5 cm) is incorrect as it is double the correct answer. Choice C (-15 cm) and choice D (-30.5 cm) are incorrect as the negative sign indicates an inverted image, but in this case, the image is upright.

Correct Answer: C

Rationale: Potential energy increases as particles approach each other because the distance between them decreases, leading to an increase in repulsive forces due to the close proximity of the particles. This causes the potential energy to rise as the particles try to move away from each other to reduce the repulsive forces. Attractive forces do not increase in this scenario, and in fact, they may decrease due to the particles being closer together. Repulsive forces increase as the particles get closer, not decrease. Therefore, the correct answer is C.