HCI 2014 P2

1 Name: __________________________________ ( ) Class: _____ HWA CHONG INSTITUTION END-OF-YEAR EXAMINATION 2014 PHYSICS Paper 2 Level: Secondary Three Duration: 1 hour 45 min Do not open this booklet until you are told to do so. INSTRUCTIONS TO CANDIDATES Write your name, index number and class on the top of this page. Answer the questions in Section A and B in the spaces provided. All workings must be shown. In Section B, for Question 10 answer ‘EITHER’ or ‘OR’. INFORMATION FOR CANDIDATES In Sections A and B the intended marks for each question or part of a question are given in brackets [ ]. Any working should be done in the space provided. When necessary, take g to be 10 ms-2 or 10 Nkg-1 ___________________________________________________________________ This question paper consists of 15 printed pages, including this page.

2 SECTION A (40 MARKS) Answer all the questions in this section 1. Pentaprism is used in a single -lens reflex camera to enable the user to see exactly what the lens of the camera views. Light entering the lens is reflected upward by a plane mirror to form an image on a piece of smoked glass. A fter two successive reflection inside t he pentaprism, light from the image emerges from the viewfinder and reaches the user's eye. (a) Explain why the plane mirror used in this system must be very thin. [2] ………………………………………………………………………………….. ………………………………………………………………………………….. ………………………………………………………………………………….. (b) Determine the maximum angle of incidence for refraction to occur when light passes from glass to air. Give that ηglass = 1.6 . [2] (c) Explain why light rays are reflected on the two sides of the pentaprism. [2] ………………………………………………………………………………….. ………………………………………………………………………………….. …………………………………………………………………………………..

3 2. William makes a glass of hot tea. After a while, he adds some ice cubes into the tea. William uses a temperature sensor to measu re the temperature of the tea. The figure below shows the temperature-time graph obtained. (a) Explain why the temperature of the tea increases from R to S. [2] ………………………………………………………………………………….. ………………………………………………………………………………….. ………………………………………………………………………………….. ………………………………………………………………………………….. (b) Estimate the temperature of the surroundings. [1] ………………………………………………………………………………….. (c) Another method to cool the hot tea without adding ice cubes is by leaving the cup of hot tea in the room to cool by evaporation. Explain how evaporation causes this cooling. [2] ………………………………………………………………………………….. ………………………………………………………………………………….. ………………………………………………………………………………….. …………………………………………………………………………………..

4 3. When a house is heated, thermal energy will be lost to the external surroundi