GRADE 8 NATURAL SCIENCES EXAM REVISION

What is the difference between luminous and non-luminous objects?

Luminous objects emit light; non-luminous objects do not emit light but can reflect it.

What is natural light?

Light that comes from natural sources, such as the Sun.

What is artificial light?

Light produced by human-made sources, such as light bulbs.

How does light travel?

Light travels in straight lines and can behave as energy.

What are transparent materials?

Materials that allow most light to pass through them, like clear glass.

What are translucent materials?

Materials that allow some light to pass through, but not clearly, like frosted glass.

What are opaque materials?

Materials that do not allow light to pass through, like wood.

What is reflection?

The bouncing back of light when it hits a surface.

What is the law of reflection?

The angle of incidence equals the angle of reflection.

What does a normal line represent in reflection?

A line perpendicular to the surface at the point of incidence.

What is diffuse reflection?

Reflection that occurs when light hits a rough surface and scatters.

What is refraction?

The bending of light as it passes from one medium to another.

What happens when light passes from air into glass?

The light slows down and bends towards the normal line.

What is dispersion in light?

The separation of light into its different colors, like passing through a prism.

What does ROYGBIV represent?

The colors of the visible spectrum: Red, Orange, Yellow, Green, Blue, Indigo, Violet.

What components make up the human eye?

Pupil, iris, lens, retina, optic nerve, and brain.

What are terrestrial planets?

Rocky planets such as Mercury, Venus, Earth, and Mars.

What are gas giants?

Planets with thick gas atmospheres, such as Jupiter and Saturn.

What are dwarf planets?

Small celestial bodies, like Pluto and Ceres, that orbit the Sun.

What is the Oort Cloud?

A spherical shell of icy bodies surrounding the solar system.

What is a comet?

An icy body that releases gas or dust as it approaches the Sun.

What are meteors?

Small rock or metal pieces that enter Earth's atmosphere and produce a visible streak.

What are meteorites?

Meteors that survive passage through the atmosphere and land on Earth.

What are the conditions necessary for life on Earth?

Oxygen, suitable temperature, water, and sunlight.

What is the purpose of optical telescopes?

To gather and magnify light from distant objects.

What is a series circuit?

A circuit where components are connected end-to-end, so the current has only one path.

What happens in a parallel circuit if one bulb stops working?

The other bulbs remain lit because there are multiple paths for the current.

What is static electricity?

A buildup of electric charge on the surface of objects.

What is the balloon-and-wool experiment?

An experiment demonstrating static electricity through friction.

What are circuit symbols?

Simple drawings that represent electrical components in a circuit.

What is a resistor?

A component that resists the flow of electric current.