Grade 8
  1. Introduction to Physics  1.1. What is physics and its scope?  1.2. Applications of Physics in Advanced Technology  1.3. The role of experiments in physics  1.4. Physics in Engineering and Medicine  1.5. The scientific method and its refinements  1.6. Emerging areas in physics
  2. Measurement and units  2.1. Advanced Physical Quantities and Their Classification  2.2. SI units and standardized measurement systems  2.3. Precision instruments for length and mass measurement  2.4. Advanced Techniques in Time Measurement  2.5. Calculating Volume Using Mathematical Formulas  2.6. Density measurement and applications  2.7. Temperature measurement with thermometers and sensors  2.8. Error analysis and minimization of systematic errors  2.9. Estimation, Approximation and Scientific Notation
  3. Kinematics and dynamics  3.1. Motion and its types – rectilinear, circular and oscillatory  3.2. Difference between distance and displacement  3.3. Speed vs Velocity – Understanding their Difference  3.4. Acceleration and its real life applications  3.5. Graphical Analysis of Motion - Interpreting Motion Graphs  3.6. Equations of motion - derivation and applications  3.7. Free fall and gravitational acceleration  3.8. Effect of air resistance on falling objects
  4. Force and Newton's laws of motion  4.1. Introduction to forces and their effects  4.2. Balanced and unbalanced forces - their role in motion  4.3. Newton's First Law - Understanding Inertia  4.4. Newton's Second Law - Mathematical Applications in Acceleration  4.5. Newton's Third Law - Action and Reaction Forces in Daily Life  4.6. Friction - its types, effects and methods of reduction  4.7. Circular motion and centripetal force  4.8. Impulse and Momentum – Real Life Examples  4.9. Application of Newton's laws in automobiles and space travel
  5. Work, Energy and Power  5.1. The concept of work and its mathematical representation  5.2. Energy and its forms – kinetic, potential, mechanical and internal  5.3. Understanding the Work-Energy Theorem  5.4. Law of Conservation of Energy – Practical Applications  5.5. Power and its units - how it differs from energy  5.6. Methods for improving the efficiency of machines and reducing energy losses  5.7. Applications of renewable and non-renewable energy in daily life
  6. Pressure and its applications  6.1. Understanding pressure in solids  6.2. Pressure in Fluids - Pascal's Principle  6.3. Atmospheric pressure and barometer  6.4. Buoyancy and Archimedes' principle  6.5. Hydraulics and its applications  6.6. Variations in pressure at depth and in high-altitude environments
  7. Heat and temperature  7.1. Heat as a form of energy  7.2. Temperature measurement using advanced sensors  7.3. Thermal expansion of solids, liquids and gases  7.4. Specific heat capacity and its applications  7.5. Heat transfer - conduction, convection and radiation  7.6. Latent heat and phase changes of matter  7.7. Thermal balance and heat exchange in everyday life
  8. Lighting and Optics  8.1. Nature of light - wave and particle theory  8.2. Reflection - laws and applications in optical instruments  8.3. Refraction and Snell's Law  8.4. Lenses - Uses in Image Formation and Corrective Lenses  8.5. Optical instruments – microscope, telescope and camera  8.6. Dispersion of light and colour formation  8.7. Total internal reflection - fibre optics and mirage creation  8.8. Human Eye and Vision Defects - Nearsightedness, Farsightedness and Astigmatism
  9. Sound and waves  9.1. Wave motion - characteristics and classification  9.2. Properties of sound - speed, pitch and intensity  9.3. Reflection and absorption of sound – echo and reverberation  9.4. Doppler effect and its applications  9.5. Ultrasound and sonography in medicine  9.6. Noise pollution and its prevention
  10. Electricity and Magnetism  10.1. Static electricity and electric charge  10.2. Electric current - conductors and insulators  10.3. Ohm's Law and Resistance  10.4. Series and Parallel Circuits – Differences and Applications  10.5. Electrical power and energy calculations  10.6. Safety measures in handling electricity  10.7. Magnetism - Properties and Field Lines  10.8. Electromagnetic Induction - Faraday's Law and Applications  10.9. Transformers and their use in electric power distribution
  11. Space science and universe  11.1. Solar System - Formation and Components  11.2. The Sun - structure, energy production and solar flares  11.3. Moon - effect of its gravity on the Earth  11.4. Eclipses – Solar and Lunar  11.5. Planets - Structure, Atmosphere and Moons  11.6. Satellites - artificial and natural  11.7. Gravity in space and its effect on astronauts  11.8. Theories of black holes and the expanding universe  11.9. Space Exploration - Rockets, Rovers and Space Stations
  12. Nuclear physics and modern applications  12.1. Structure of atom - protons, neutrons and electrons  12.2. Radioactivity - types and sources  12.3. Half-life and radioactive decay  12.4. The use of radioisotopes in medicine and industry  12.5. Nuclear fission and fusion – electricity generation
  13. Environmental Physics  13.1. Impact of energy consumption on the environment  13.2. Global warming and climate change - physics perspective  13.3. Sustainable energy – solar, wind and hydroelectric power  13.4. Role of Physics in Weather Forecasting  13.5. Physics of Natural Disasters - Earthquakes, Tsunamis and Tornadoes

Grade 8 → Lighting and Optics ↓


Optical instruments – microscope, telescope and camera


Light and optics play an important role in the field of physics. One of the most interesting aspects of optics is how we use optical instruments. This includes instruments such as microscopes, telescopes, and cameras. These instruments are powerful tools that enhance our natural vision, allowing us to see distant planets, study tiny cells, and capture precious moments of life.

Microscope

A microscope is an instrument that magnifies small objects, allowing us to see details that are invisible to the naked eye. Microscopes are important in biology and medicine, as they help scientists study the structure of cells, bacteria and other tiny organisms.

How microscopes work

A typical microscope uses lenses to bend light and magnify images. The most common type of microscope is the optical or light microscope, which uses glass lenses. Here's how it works:

  • Objective lens: This lens is located near the specimen, which collects light and magnifies the image.
  • Eyepiece lens: The eyepiece lens, which you look through, magnifies the image.
  • Stage: The platform where the sample is placed.
  • Light source: A lamp, or sometimes a mirror, that illuminates the specimen.

The total magnification of a microscope is the product of the magnification of the objective lens and the eye-piece lens.

Example:

If the magnification of the objective lens is 40x and the magnification of the eyepiece lens is 10x, then the total magnification is:

Total Magnification = Objective Magnification x Eyepiece Magnification = 40 x 10 = 400

Visualization of how a microscope works

stageEyepieceObjective

Telescope

Telescopes are another type of optical instrument that allows us to see distant objects such as stars and planets. While microscopes make small objects appear larger, telescopes make distant objects appear closer.

Types of telescopes

There are different types of telescopes, but the main two are:

  • Refracting telescopes: use lenses to bend light into a focal point.
  • Reflecting telescopes: Use a mirror instead of a lens to reflect light to a focal point.

How do binoculars work?

The structure of telescopes is simple. The main components of a refracting telescope work as follows:

  • Objective lens: Captures and focuses the light coming from distant objects.
  • Eyepiece lens: magnifies the light and produces a viewable image.

Visualization of a refracting telescope

objective lensEyepiece Lens

Use the formula below to calculate the magnification of a telescope:

Example:

If the focal length of the objective lens is 1000 mm and the focal length of the eye-piece lens is 20 mm, then the magnification will be:

Magnification = Focal length of objective / Focal length of eyepiece = 1000 / 20 = 50

Camera

Cameras are devices used to capture images. Unlike microscopes and telescopes, cameras not only allow us to see things but also record them. Modern cameras, including the ones on your smartphone, are a perfect example of optical devices in daily use.

How cameras work

A camera works by allowing light to pass through the lens to capture an image on a sensitive surface (originally film, now usually a digital sensor). Here's how a basic camera works:

  • Lens: Focuses light to form an image on the recording surface.
  • Aperture: The hole in the lens that controls the amount of light that enters. It acts like the pupil of the eye.
  • Shutter: A device that opens and closes to control the amount of time light falls on the recording surface.
  • Sensor: The surface where light is captured to form an image. In digital cameras, this is a digital sensor.

Visualizing the camera

LensSensor

Formulas in photography

In photography, a key concept is exposure, which depends on three factors - aperture, shutter speed, and ISO. Changing these affects the brightness of your photo:

  • Aperture: Measured in f-stops (e.g., f/2.8, f/16), smaller numbers mean larger openings.
  • Shutter speed: Measured in seconds (e.g., 1/1000s, 1s), faster speeds freeze motion.
  • ISO: Camera sensor sensitivity, higher number means more sensitivity to light.

Conclusion

Microscopes, telescopes and cameras are fascinating optical instruments that use lenses and mirrors to control light, giving us new ways to explore and understand the world. All of these instruments rely on the basic principles of optics to work. By learning about these instruments, we gain insight into how light behaves and how we can use this knowledge to enhance human vision and share our experiences.


Grade 8 → 8.5


U
username
0%
completed in Grade 8

← Prev (8.4)
Lenses - Uses in Image Formation and Corrective Lenses
Next (8.6) →
Dispersion of light and colour formation

Comments 



Optical instruments – microscope, telescope and camera

https://www.physicsflow.com/g8/8.5?pfal=en