An instrument used in labs to mix liquids using a rotating magnetic field is a:

Appeared in: AIIMS CRE, SNO-2024

Explanation

the magnetic stirrer, which is specifically designed for mixing liquids.
Its core mechanism involves a rotating magnetic field generated in the base of the unit.
This field interacts with a small, coated magnet (a stir bar or 'flea') placed inside the liquid container.
As the external field rotates, it forces the stir bar to spin, creating a vortex that thoroughly mixes the liquid.

Option A: A centrifuge is used for separation, not mixing. It spins samples at high speed to separate components based on their density.
Option C: An incubator provides a controlled environment (temperature, humidity, CO2) to support the growth of microbiological cultures or cell cultures. It does not mix liquids.
Option D: An autoclave is a sterilization device. It uses high-pressure steam to kill microorganisms, including bacteria, viruses, and spores, on equipment and supplies.

Visual 1: Infographic - A comparative chart showing images of a magnetic stirrer, centrifuge, incubator, and autoclave, each with a brief description of its function. This helps in visually differentiating the equipment.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Laboratory Equipment Functions as background academic context rather than a clinical decision trigger.
Understanding the function of basic lab equipment is crucial for nurses, especially those working in research, specialized clinics, or advanced practice roles where they might handle specimens or prepare solutions.
For example, a centrifuge is used daily to prepare blood samples for analysis, an autoclave is essential for ensuring surgical instruments are sterile to prevent patient infections, and an incubator is vital for microbiology labs to identify pathogens from patient samples.
What if? - If a nurse needed to gently resuspend settled red blood cells in a plasma bag before transfusion, they would use gentle manual inversion, not a magnetic stirrer, as the mechanical force could damage the cells (hemolysis).

How to Approach the Question

First, identify the key function described in the question stem: 'mix liquids'.
Next, identify the specific mechanism mentioned: 'using a rotating magnetic field'.
Review the options and recall the primary function of each piece of equipment.
A centrifuge separates, an incubator controls environment, and an autoclave sterilizes.
A magnetic stirrer is the only option whose function is to mix, and it does so using the exact mechanism described.
Therefore, match the function and mechanism from the stem to the correct instrument.

Concept Tested & Keywords

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Practise the full AIIMS CRE, SNO-2024

Attempt every question from this paper in a timed mock, then review the full solution for each one.