Lesson Notes By Weeks and Term v4 - JHS 3
ENERGY
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
ENERGY
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
Subject: Science
Class: JHS 3
Term: 2nd Term
Week: 7
Grade code: B9.4.1.2.2
Strand code: 4
Sub-strand code: 1
Content standard code: B9.4.1.2
Indicator code: B9.4.1.2.2
Theme: FORCES AND ENERGY
Subtheme: ENERGY
This page supports the lesson note with a companion video and a short classroom-ready summary.
For class groups and homework, share this lesson page so learners also get the summary, objectives, and full lesson context.
Cameras are used every day in Ghana—on mobile phones for selfies, in schools for projects, by journalists for news, and by traders to advertise products online. Understanding how a camera forms an image helps learners explain common issues like *blurred photos, dark pictures, and why the image appears upside down inside the camera before it is corrected*. This topic links to Energy because cameras depend on light energy and how it travels and is focused by lenses to form images.
2.1 Light as Energy (Link to ENERGY) Light is a form of energy that travels in straight lines (as rays) from a source or from objects that reflect light. A camera does not “create” an image by itself; it controls and focuses light energy to form an image.
Key idea: *No light → no image.*
2.2 Main Parts of a Camera and Their Functions A simple camera (including phone camera) has these key parts: Lens (Convex/Converging lens) Bends (refracts) light rays to bring them to a focus. Forms a real image on the film/sensor. Aperture (Opening / diaphragm) Controls the amount of light entering the camera. Large aperture → more light → brighter image (but may reduce depth of field). Small aperture → less light → darker image (but sharper depth of field). Shutter Controls the time light is allowed to enter. Fast shutter (short time) → less light → darker but freezes motion. Slow shutter (long time) → more light → brighter but can blur moving objects. Film (old cameras) / Image sensor (digital cameras/phones) The surface where the image is formed and recorded. In digital cameras, the sensor converts light energy into electrical signals. Camera body (light-tight box) Prevents unwanted light from entering. Ensures only light passing through the lens forms the image.
2.3 How an Image is Formed in a Camera (Step-by-step) Step 1: Light leaves the object The object may emit light (e.g., a bulb) or reflect light (e.g., a person’s face in daylight).