7 CLASS FA 4 LAB
ACTIVITY
NAME
OF THE EXPERIMENT
To Show that Sunlight Consists of
Seven Colours Using a Prism
Aim:
To show that sunlight consists of
seven different colours by passing it through a glass prism.
Materials
Required:
Glass prism
White screen / white chart paper
Cardboard with a small hole
Dark room or shaded area near a
window
Procedure:
A dark room was arranged by
closing the windows and doors, leaving a small opening for sunlight.
A cardboard with a small hole was
fixed on the window to allow a narrow beam of sunlight to enter the room.
A glass prism was placed in the
path of the sunlight.
A white screen or chart paper was
placed on the other side of the prism.
The position of the prism and the
screen was adjusted until a clear band of colours was obtained on the screen.
Observation:
A band of seven different colours
was observed on the white screen. The colours appeared in the following order:
violet, indigo, blue, green, yellow, orange, and red.
Results
and Discussion:
When sunlight passed through the
glass prism, it split into seven colours. This phenomenon is called dispersion
of light. Each colour bent through a different angle because different colours
have different wavelengths. Hence, a spectrum of seven colours was formed on
the screen.
Inference:
Sunlight is a mixture of seven
colours, namely violet, indigo, blue, green, yellow, orange, and red (VIBGYOR).
Precautions:
The prism and screen were kept
clean for clear observation.
The experiment was performed in a
controlled dark environment for better visibility.
