Table of Contents
Activity 11.6- Focusing Sunlight with a Concave Mirror
Objective- To demonstrate how a concave mirror can focus sunlight to form a real image of the sun.
Materials Needed-
- A concave mirror (a mirror that curves inward).
- A screen, like a white paper or a wall.
- A sunny day (to have clear sunlight).
Safety Note- Be very careful while handling the concave mirror in sunlight. The focused sunlight can be very intense and may cause burns or fire.
Procedure-
- Outdoor Setup- Take the concave mirror and the screen outside on a sunny day.
- Angle the Mirror- Hold the concave mirror towards the sun. The mirror should catch the sunlight and reflect it.
- Find the Focus- Slowly move the screen closer or further away from the mirror until you find a point where a bright spot of light forms on the screen. This is the focus of the mirror.
- Observe the Sun’s Image- At the focus, you should see a small, bright, and well-defined image of the sun on the screen.
Also Check – Class 7 Science -Chapter 15 – Light- Complete Notes
Also Check – Chapter 11- A Detailed Guide to the Light Activities for Class 7 Students
Core Concepts Explained-
- Concave Mirrors and Focusing- Concave mirrors curve inward, like a bowl. They have the property of converging (bringing together) light rays that are parallel, like sunlight.
- Real Image Formation- The image of the sun formed on the screen is a ‘real image’. This means it is formed by actual light rays converging at a point. Real images can be captured on a screen.
- The Sun’s Image- The image of the sun will be small and bright. It’s a miniaturised, accurate representation of the sun.
Possible Questions and Answers-
Why does the mirror need to be concave?
- A concave mirror converges light rays to a focal point. This focusing effect is necessary to form a real image on a screen.
Can we do this activity with any mirror?
- No, only concave mirrors can converge light rays effectively to form a real image like this.
Why can’t we use a convex mirror or a flat mirror for this?
- Convex mirrors diverge light rays, and flat mirrors don’t change the path of light rays enough to focus them to a point.
Is it safe to look at the focused sunlight?
- No, it’s not safe to look directly at the focused sunlight or the sun’s image on the screen. It can be very bright and may harm your eyes.
Can this mirror start a fire?
- Yes, the focused light from a concave mirror can be intense enough to start a fire, so it’s important to be very careful during this activity.
