Pers 2. (a) Calculate the virtual depth of a black dot at the
bottom of a cubic block made of transparent glass with each
side 4 cm, while the refractive index of glass is 1.6.​

2.5 cm

Explanation:

Using the relation :

Refractive index = Real Depth / Apparent depth

Refractive index = 1.6

Real depth = 4cm

Virtual depth = apparent depth = x

1.6 = 4cm / x

1.6x = 4

x = 4 / 1.6

x = 2.5

Hence, virtual depth = 2.5cm

1/0.14nm = 10^10/1.4 a lot

a.metals can become magnetic if they have many spinning electrons that create magnetic fields.d.only some metals are attracted by magnets; these metals are called ferromagnetic.

d.wrapping an insulated wire around a metal with ferromagnetic properties and applying an electric current.