2014 WAEC Physics Practical You are provided with an illuminated object, converging lens, screen, metre rule, and other necessary...

Physics

WAEC 2014

Open Photo

You are provided with an illuminated object, converging lens, screen, metre rule, and other necessary materials.

Measure and record the size a\(_{o}\) of the illuminated object.
Place the object O and the screen S on Opposite sides of the converging lens L.
Set the distance between the object and the lens U = 30cm.
Adjust the screen until a sharp image of the illuminated object is obtained on the screen.
Measure and record the size a of the image.
Evaluate m = \(\frac{a}{a_{0}}\), and m\(^{-1}\)
Repeat the procedure for four other values of U=35cm, 40cm, 45cm and 50cm respectively.
Tabulate your readings.
Plot a graph with m\(^{-1}\) on the vertical axis and U on the horizontal axis.
Determine the slope, s, of the graph and intercept, C, on the vertical axis.
Determine the value of U for which m\(^{-1}\)=0.
State two precautions taken to obtain accurate results.

(b)i. Using your graph, determine the value of m for which U= 37cm.

ii. Sketch a diagram to illustrate how a converging lens may be used to produce a real diminished image of an object.

Your School's Whatsapp Group - Join Us now

WAEC and NECO CBT Software for Computers and Laptops - Candidates, Schools, Centres, Resellers - 100% Offline -Download Now

Explanation

a = 1.5cm

u/cm	\(\frac{a}{cm}\)	M=\(\frac{a}{d}\)	m\(^{-1}\)
30.0	2.2	1.467	0.682
35.0	1.5	1.000	1.000
40.0	1.2	0.800	1.250
45.0	0.9	0.600	1.667
50.0	0.7	0.467	2.141

Slope (s) = \(\frac{\bigtriangleup {m}^{-1}}{\bigtriangleup {y}}\) = \(\frac{2.4 - 0.4}{54 - 24} = \frac{2}{30}\) = 0.06

X\(_{1}\) = when m\(^{-1}\) = 0
u = 23cm

Precautions; i

- avoided error due to parallel when taking readings on the metre rule.
- made sure that, I took the height of the image when it is sharp.
- ensured that the intensity of the source of light was maintained.
- took repeated readings to avoid random errors.

Open Photo