Explanation

• The pupil is the opening in the center of the iris that regulates the amount of light entering the eye, similar to the aperture in a camera.
• The iris controls the size of the pupil, adjusting the amount of light that reaches the retina.

Explanation

The retina is the innermost layer of the eye that senses light and sends visual signals to the brain, much like the film in a camera captures images.

Explanation

• The optical centre is the point within a lens where a ray of light passes through without changing its direction or path.
• This point is located at the centre of the lens, on the optical axis.

Explanation

A converging lens (also known as a convex lens) refracts parallel rays of light and converges them at a single point, called the focal point.

Explanation

• Air expands the most for a given rise in temperature, due to its low density and high thermal expansion coefficient.
• This is why hot air rises and cool air sinks, driving convection currents in the atmosphere.

Explanation

• In a mercury thermometer, the mercury in the bulb expands and rises in the tube, which has a linear scale ranging from 35°C to 42°C.
• This range is typically used for medical thermometers to measure human body temperature.

Explanation

• A rivet is used to fasten two hard materials together.
• Such as metal plates or sheets.

Explanation

• Water has its minimum density at 0°C.
• Water has its maximum density at 4°C.

Explanation

• Thermal Contraction is the decrease in size (length, area, and volume) of a body due to a decrease in temperature.
• Thermal Expansion is the opposite phenomenon, where the size increases due to an increase in temperature.

Explanation

• Thermal Expansion is the natural increase in size of a substance as its temperature increases.
• It's a common phenomenon in solids, liquids, and gases.