Acell phone is placed 25 cm in front of a diverging lens with focal length of magnitude 20 cm. how far is the image of this phone from the lens?

-11.11 cm

Explanation:

The lens formula is defined as,

Here, f is the focal length, u is the distance of an object, v is the distance of image.

Given that, the diverging lens is given so according to sign convention of diverging less, u and f should be negative.

Given that, distance of an cell phone in front of a diverging lens is

And its focal length is .

Put the variables in lens formula. Therefore,

Therefore the image is formed of this phone at a distance of -11.11 cm from the lens.

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