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Name: ___________________________________ Class Reg. No: ( _____ )Class: __________

ST. PATRICKS SCHOOL

PRELIMINARY EXAMINATIONS 2011

Subject :SCIENCE (Physics/Chemistry) Paper 55116/05

Date : 31 August 2011

Level :SECONDARY 4 EXPRESS /5 NORMAL (ACADEMIC)

Time :

1 hour 30 min

(For bothPhys

icsandChemistryquestions)

INSTRUCTIONS TO CANDIDATES

1. Write your name, class and index number on this Question Paper and Answer Booklet.

2. Write in dark blue or black pen in the spaces provided in the booklet. You may use a softpencil for any diagrams, graphs or rough working. Do not use staples, paper clips,highlighters, glue or correction fluid.

3. All your answers should be written in this booklet.

4. Tie the graph paper to the answer booklet with the string provided.

For Markers Use Only

For Examiners Use

Total 15

This Answer Booklet has 3 printed pages including the cover page

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1. Aim: To determine the focal length, f, of a lens.

Procedure:

(a) Measure the height h of the object, as shown in the diagram below.

h = __________ cm [ 1 ]

(b) Set up the apparatus as shown in the diagram below. Adjust the retortstand such that the light source is shining through the centre of the lens.

(c) Place the lens a distance x(30 cm) away from the illuminated object.

(d) Place the screen close to the lens and move it away from the lens until the

sharpest image is obtained on the screen. Do not move the object and lenswhile you do so.

(e) Measure the distance y from the lens to the image. Measure the height kofthe image, as shown in the diagram below.

2

light source

x y

lens screen

h

k

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(f) Repeat steps (c) to (e) to obtain at least five sets of readings ofy and kinthe table below. The distance xshould be in the range of 30 cm to 50 cm. [ 3 ]

x / cm y / cm k / cm

(g) Plot a graph ofy against k. [ 4 ]

(h) Determine the gradient, G, of the graph.

Gradient, G= _________ [ 2 ]

(i) Calculate the focal length, f, of the lens, given that f= Gh.

Focal length of the lens, f= __________ cm [ 2 ]

(j) State one source of error.

____________________________________________________________________________________________________________________ [ 1 ]

(k) Suggest an improvement. Explain why your suggestion would reduce thissource of error.

Improvement: _________________________________________________________________________________________________________

Explanantion: _______________________________________________

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__________________________________________________________ [ 2 ]

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