Omar wrote a hypothesis about batteries called dry cells.

If more dry cells are connected end to end, a light bulb will work longer because there is more energy available.

What are the variables in his hypothesis?

The independent variable is the number of dry cells, and the dependent variable is the length of time the bulb works.
The independent variable is the length of time the bulb works, and the dependent variable is the number of dry cells.
The independent variable is the number of dry cells, and the dependent variable is the amount of energy available.
The independent variable is the amount of energy available, and the dependent variable is the number of dry cells.

The independent variable is the number of dry cells, and the dependent variable is the length of time the bulb works.

Explanation:

From this experiment, we can clearly ascertain that the dependent variable is the length of time the bulb works and the independent variable is the number of dry cells.

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia

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