ICSE Class 8 Physics, Unit 5: Light Energy
From the CISCE curriculum. 8 key concepts, about 3 days of study at 20 to 30 minutes a day.
What this unit aims at
An object lying at the bottom of a vessel filled with water usually appear to be at different depth than it actually is. This is due to bending of light rays when it travels from water to air. This phenomenon is called refraction. Light bends when it passes obliquely from one medium to the other. Due to refraction, a mirage is observed on a hot sandy desert. Atmosphere also refract the rays coming from the sun. This causes advanced sunrise and delayed sunset. Previous learning emphasized on reflection of light by a plane mirror. how images are formed by a curved (concave) mirror is now dwelt upon along with rules used to construct ray diagrams.
Your child should be able to
- define refraction
- discuss examples of refraction
- describe a spherical mirror
- describe a concave and a convex mirror
- define the terms, principal axis, centre and radius of curvature, focus and focal length for a spherical mirror
- describe rules for making ray diagrams for spherical mirror
- distinguish between real and virtual images
- use a ray diagram to show formation of a real image by a spherical mirror
- describe the characteristics of a real image formed by a spherical mirror
- describe dispersion of white light by a prism into constituent colours
Key concepts in this unit
- Refraction:
- Definition Examples of Refraction.
- Curved Mirrors:
- Convex Concave Reflecting surface (Convex and Concave)
- Uses of Curved mirrors Terms related to Curved mirrors –Focus, Principal Axis, centre of curvature, radius of curvature
- Rules for making ray diagrams of Spherical mirrors.
- Real and Virtual Images Ray diagrams with curved mirrors where real images are formed.
- Dispersion of white light into constituent colours.
Teach this unit at home
- A day-by-day plan from the CISCE concepts, so you know what to cover each day.
- A step-by-step script for each day, so you know what to say and ask (AI-written from the CISCE curriculum, so check it against your child's school book).
- A quiz at the end.
From the CISCE Curriculum for Classes I to VIII (2016). CISCE sets what is taught, not the textbooks, so schools use different books and there are no page numbers here. Adhian Gurus is not affiliated with CISCE.