What type of lens does a magnifying glass use?
A converging (convex) lens.
What type of image does a magnifying glass produce?
Magnified, erect, and virtual.
Where must an object be placed for a magnifying glass to work?
Between the optical center and the principal focus of the lens.
What are the two lenses in a compound microscope?
The objective lens and the eyepiece lens.
What is the function of the objective lens in a compound microscope?
It forms a magnified real image of the object.
What is the role of the eyepiece in a compound microscope?
It magnifies the image formed by the objective lens.
Where is the final image of a compound microscope formed?
At the least distance of distinct vision.
What type of optical instrument is used to view distant objects like stars?
An astronomical telescope.
What type of image does an astronomical telescope produce?
An inverted image.
What are the two lenses in an astronomical telescope?
A long focal length objective lens and a short focal length eyepiece.
Where is the final image of a telescope formed?
At infinity.
What part of the eye controls the amount of light entering?
The iris.
What type of image is formed on the retina?
A real and inverted image.
What causes hypermetropia (long-sightedness)?
Short eyeball or weak lens causing image formation behind the retina.
How is hypermetropia corrected?
Using a converging lens.
What causes myopia (short-sightedness)?
The eyeball is too long or the lens is too strong, forming images in front of the retina.
How is myopia corrected?
Using a diverging lens.
What are the light-sensitive receptors of the eye called?
They are located on the retina.
What does the shutter of a camera do?
It controls the duration of exposure to light.
What does the diaphragm of a camera control?
The size of the aperture and the amount of light entering.
What part of the camera corresponds to the pupil of the eye?
The aperture.
What part of the camera corresponds to the retina?
The film or sensor.
What part of the eye corresponds to the camera diaphragm?
The iris.
How does a slide projector form its image?
It uses a convex lens to produce a real, inverted, magnified image on a screen.
Where is the slide placed relative to the lens in a projector?
Between f and 2f of the projection lens.
What is the function of the condenser in a slide projector?
It concentrates and directs light onto the slide, ensuring even illumination.
What principle enables optical fibres to transmit light?
Total internal reflection.
What is the purpose of the cladding in optical fibres?
To create a lower refractive index boundary for total internal reflection and to provide mechanical strength.
Why can optical fibres carry many more signals than metal cables?
Because optical frequencies (~10¹⁵ Hz) are much higher than radio frequencies (~10¹⁰ Hz).
Give two advantages of optical fibre communication.
Lightweight, immune to interference, secure, low energy loss, and capable of high data transmission.
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