Condition 2 [2]
(b) Fig.6.1 shows a uniform metre rule PQ in equilibrium.
F
10 cm
40cm
pivot
0.50N
Fig.6.1
The distance PQ is 100cm. The mass of the metre rule is 0.12 kg and its weight is W.
(1) On Fig 6.1, draw and label:
1. an arrow to show the force W acting on PQ at the centre of mass
2. an arrow to show the force R acting on PQ at the pivot.
[2]
(ii) By taking moments about the pivot, calculate F.

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