Experiment to determine the focal length of a convex lens
FOCAL LENGTH = 9.5cm
Focal length
(cm) 1st reading of mark I1
(cm) 2nd reading of mark I2
(cm) Distance (cm) Separation of object distance and the screen (cm) D^2-d^2
(cm)
4 15.90 22.20 6.30 38.00 1404.31
5 14.40 17.10 2.70 47.50 2248.96
6 13.40 15.70 2.30 57.00 3243.71
7 13.00 14.00 1.00 66.50 4421.25
8 12.60 13.50 0.90 76.00 5775.19
9 12.10 12.80 0.70 85.50 7309.76

Plot a graph of D^2-d^2
Determine the scale of the graph
What is the gradient of the graph
Show that the gradient of the graph is equal to the focal length

Question

Experiment to determine the focal length of a convex lens
         FOCAL LENGTH = 9.5cm
Focal length
(cm)	1st reading of mark I1
(cm)	2nd reading of mark I2 
(cm)	Distance  (cm)	Separation of object distance and the screen (cm)	D^2-d^2
(cm)
4	15.90	22.20	6.30	38.00	1404.31
5	14.40	17.10	2.70	47.50	2248.96
6	13.40	15.70	2.30	57.00	3243.71
7	13.00	14.00	1.00	66.50	4421.25
8	12.60	13.50	0.90	76.00	5775.19
9	12.10	12.80	0.70	85.50	7309.76

Plot a graph of D^2-d^2
	Determine the scale of the graph
	What is the gradient of the graph
	Show that the gradient of the graph is equal to the focal length