The question asks about the material typically used to fill the bulb of a hydrometer. A hydrometer is an instrument used to measure the relative density or specific gravity of liquids. Its operation relies on Archimedes' principle, which states that a floating object displaces a weight of fluid equal to its own weight. To function correctly, a hydrometer needs to float upright and be sensitive to changes in liquid density. This requires a specific design to ensure stability and proper immersion.
Correct Option: D) Lead shot. Lead shot is used to weight the bulb of a hydrometer. Its high density ensures that the hydrometer floats upright and sinks to the appropriate level in liquids, allowing for accurate density measurements.
To understand the role of buoyancy in a hydrometer, we need to recall Archimedes' principle and how it applies to floating objects. A hydrometer floats in a liquid, and the depth to which it sinks depends on the density of the liquid and the buoyant force exerted by the liquid.
Correct Option: A) It determines the depth of submersion. This is correct because the buoyant force, which balances the weight of the hydrometer, depends on the density of the liquid. A denser liquid provides sufficient buoyant force with less submerged volume, so the hydrometer floats higher (less depth of submersion). A less dense liquid requires more submerged volume to generate the same buoyant force, so the hydrometer sinks deeper (greater depth of submersion).
The question asks for the specific name of a hydrometer used to measure the density of alcohol. We need to identify the instrument designed for this particular purpose among the given options.
An alcoholmeter is a type of hydrometer used for determining the alcoholic strength of liquids, typically by measuring their density. The other options are for different substances.
C) Alcoholmeter: This is the correct term for a hydrometer specifically designed to measure the density or alcoholic strength of alcohol-water mixtures.
This question tests the understanding of Archimedes' principle and the concept of buoyancy, specifically how a hydrometer works. A hydrometer measures the density of a liquid based on how much it floats. The buoyant force acting on a floating object is equal to the weight of the liquid displaced by the object.
A) It floats higher. As explained, in a denser liquid, a smaller volume needs to be submerged to displace enough liquid to match the hydrometer's weight. This results in the hydrometer floating higher.
The question asks about the standard reference point for calibrating a hydrometer. A hydrometer measures the specific gravity or relative density of liquids. Its calibration relies on a known, stable reference liquid whose density is well-defined at a specific temperature. Water is typically used as this reference, and its density varies with temperature.
A) Water at 4°C — Water at 4°C has its maximum density, making it the most stable and precise reference point for calibrating instruments like hydrometers that measure specific gravity or relative density. This is a universally accepted standard in metrology.
This question relates to Archimedes' principle and the concept of buoyancy. A hydrometer measures the density of a liquid based on how much it floats. The key principle is that a floating object displaces a weight of fluid equal to its own weight.
C) Float higher. As explained, a higher liquid density means the hydrometer needs to displace less volume of that liquid to generate a buoyant force equal to its weight. Therefore, it will float higher.