Correct Answer: A

Rationale: In a parallel circuit, the current through each component is the same. This is because the components in a parallel circuit are connected across the same voltage source, so they all experience the same voltage across their terminals. The total current entering the parallel circuit is then split up among the various components, but the current through each component remains the same as the total current. Choices B, C, and D are incorrect. In a parallel circuit, voltage across each component may vary, resistance may differ, and wattage is related to power, not the equality of current through each component.

Correct Answer: A

Rationale: Density is calculated by dividing the mass of an object by its volume. The density of object A is 6.5 g / 16.25 cm3 = 0.4 g/cm3. The density of object B is 80 g / 32 cm3 = 2.5 g/cm3. The density of object C is 48 g / 22 cm3 = 2.18 g/cm3. The density of object D is 100 g / 250 cm3 = 0.4 g/cm3. Objects A and D have the same density of 0.4 g/cm3. Therefore, the correct answer is A as it has the same density as object D, making them the only objects with a density of 0.4 g/cm3.

Correct Answer: B

Rationale: The diameter of a loop is calculated by multiplying the radius by 2. Since the radius is 6 meters, the diameter is 6 2 = 12 meters. Therefore, the correct answer is 12 meters. Choice A (6 m) is the radius, not the diameter. Choices C (18 m) and D (36 m) are incorrect as they do not reflect the correct calculation for determining the diameter of a loop.

Correct Answer: C

Rationale: Electric motors convert electrical energy into mechanical energy. When electricity passes through the coils in the motor, it creates a magnetic field that interacts with the field from the permanent magnets, resulting in a force that drives motion. Choice A, 'Thermal energy,' is incorrect as electric motors are designed to minimize heat production. Choice B, 'Light,' is incorrect as electric motors do not produce light as a primary output. Choice D, 'Sound waves,' is incorrect as the primary output of an electric motor is mechanical motion, not sound waves.

Correct Answer: B

Rationale: In Einstein's mass-energy equation, E=mc^2, the symbol 'c' represents the speed of light in a vacuum, which is approximately equal to 3.00 x 10^8 meters per second. This equation demonstrates the equivalence of energy (E) and mass (m) and is a fundamental concept in the theory of relativity. Choice A is incorrect as 'c' does not represent distance in centimeters. Choice C is incorrect as 'c' does not represent degrees Celsius. Choice D is incorrect as 'c' does not represent centrifugal force.