Glass that is transparent to visible light absorbs nearly all UVB. This is the wavelength range that can cause a sunburn, so it’s true you can’t get a sunburn through glass. However, UVA is much closer to the visible spectrum than UVB. About 75% of UVA passes through ordinary glass.

Glass absorbs different amounts of light at different wavelengths. For UV light it is already virtually opaque, but even for the visible part of the spectrum it isn’t perfectly transparent. An ordinary three-millimetre (0.1-inch) sheet of window glass lets about 91 per cent of light pass.

The material thus appears as opaque to that wavelength. Beyond the range of UV light (wavelength >400 nm), the energy of visible and infrared light are not enough to excite the electrons and most of the incident light gets transmitted. Thus glass appears transparent to visible and infrared light.

If the vibrational energy of a light wave is passed through the object, then the object appears clear, or transparent. If the energy only causes vibrations in the surface before reflecting off the object, then the object appears opaque. Therefore, opacity is caused by the reflection of light waves.

Examples of translucent objects also include everyday materials.

• frosted glass shower door.
• tinted car window.
• sunglasses.
• wax paper.
• single piece of tissue paper.
• vegetable oil.
• sauteed onions.

Examples of transparent items are glass, water, and air….Materials:

• Flashlight.
• Wax paper.
• Plastic wrap.
• Tissue paper.
• Styrofoam plates.
• Clear plastic lids.
• Colored plastic lids.
• Any item that can be classified as opaque, translucent, and transparent.

Wax paper and tissue paper are translucent and light that transmits through them is scattered and fuzzy. Opaque objects absorb or reflect all of the light and do not allow any light to pass through them. Brick, stone, and metals are opaque.

Translucent materials allow some light to pass through. Transparent materials allow almost all light to pass through. Mirrors and shiny materials, such as aluminum foil, reflect light.

Light cannot go through some materials as they are opaque; these include wood, cardboard and concrete. Other materials allow some light through but you cannot see through them – they are translucent (to some extent). Examples of these include thin paper and frosted glass.

Translucent means it has colour, but you still can see through it, like apple juice. Pure water is transparent.”

Fog and mist are translucent because objects behind them can be seen but not clearly. Thick fog is opaque.

Wires of the wire mesh are opaque. But overall it can be called translucent as it allows some of the light to pass through. wire mesh is a opaque object.

Milk is a liquid so it is opaque .

Based on the above definitions we can classify the objects as opaque, transparent, translucent, luminous and non-luminous. Opaque: A piece of rock, a sheet of aluminium, a mirror, a wooden board, a CD, an umbrella, a wall, a sheet of carbon paper, a sheet of cardboard. Transparent: Air, water, a sheet of plane glass.