MODUL BERFOKUS FIZIK JPNPP 2015PHYSICS PAPER 2

BAB CAHAYA

1.(R)

Diagram below shows a ray of light passing into a glass block, the refractive index of the glass is 1.54. What is the angle of incidence?Rajah di bawahmenunjukkansatusinarcahayamelaluisatubongkahkaca. Indeksbiasanbagikacaituialah 1.54. Berapakahsuduttuju?

1.

Refractive index =

sin isin r

1.54 =

sin isin 32

Angle of incidence, i = 54.7o

2.(R)

Diagram below shows the path of light from P to Q.If the critical angle of water is 48o, which is the correct path of light after passing through point O.Rajah di bawahmenunjukkanlintasancahayadari P ke Q.Sekiranyasudutkritikal air ialah 48o, di manakahjejaksinar yang betulselepascahayaterpancarmelaluititik O.

2. Answer: S

Air udara

Water air

P

R

S

T

U

O

48o

Air udara

Glass blockbongkahkaca

32o

F

3. Diagram below shows three parallel rays are directed to a concave and a convex mirror, draw the reflected rays and indicate the focal point, F in each case. Show the direction of reflected ray. Relate the relation between centre of curvature, C, with focal point, F, of a mirror.Rajah di bawahmenunjukkan 3 sinar yang selaridipancarkeatascermincekungdancembung, lukissinarpantulandanmenandakantitik focus, F padasetiapkesberkenaan. Tunjukkanarahsinarpantulan. Kaitkanhubungan di antarapusatbulatan C dengantitik focus F bagicermintersebut.

3.

4. Diagram below shows a student standing 3 m from a plane mirror in a room. The student can see the

F

image of the wall clock located 2 m behind him.Rajah di bawah menunjukkan seoran pelajar berdiri 3 m dari cermin satah dalam sebuah bilik. Pelajar itu ternampak imej sebuah jam dinding yang tergantung 2 m daripada belakang dia.

Diagram below shows the top view of the student in the room.Rajah di bawahmenunjukkanpandangandaripadaataspelajardalambilikitu.

(a) Name the light phenomenon that enables the student to see the image of the wall clock in the plane mirror.Namakanfenomenacahaya yang menyebabkanpelajarituternampakimej jam dindingdalamcerminsatahitu.

[1 mark](b) What is the distance between the student and the image of the wall clock?

Apakahjarak di antarapelajardanimej jam dindingitu?[1 mark]

(c) The student then moves 1 m towards the plane mirror.What is the distance between the student and the image if the wall clock?Pelajaritubergerak 1 m kearahcerminsatah.Apakahjarak di antarapelajardanimej jam dinding?

[1 mark](d) The time shown by the wall clock is 9 a.m..

By drawing the hands of the clock in Diagram below, complete the image of the wall clock in the plane mirror as seen by the student.

[1 mark](e) The student moves to position X. He can see the image of the lamp in the plane

mirror. In diagram below, draw a ray diagram to show how the student can see the image of the lamp.

[1 mark]4 (a) Reflection

(b) 3 m + 5 m = 8 m

(c) 2 m + 5 m = 7 m(d)

(e)

5. Figure below shows Ahmad is looking at a fish in a pond. The fish appear to be nearer to the surface of the water.Rajah di bawahmenunjuk Ahmad sedangmemandang kea rah seekorikan yang berada di daamkolam. Ikanitukelihatanlebihdekatkepadapermukaan air.

(a) (i) Name the light phenomenon involved.Namakanfenomenacahaya yang terlibat.

[1 mark]

(ii) Explain how the above phenomenon takes place.Terangkanbagaimanafenomena di atasberlaku.

[3 marks]

(iii)

Using Figure above, draw the ray diagram that shows the formation of the fish image in the water.Denganmenggunakanrahah di atas, lukisgarisansinaruntukmenunjukkanpembentukanimejikan di dalam air.

[2 marks]

(b) The fish is 3 m from the surface of the point. If the refractive index of the water is 1.33, what is the apparent depth of the fish as observed by the Ahmad?Ikantuberada 3 m dalamdaripadapermukaan air. Sekiranyaindekspembiasan air ialah 1.33, apakah apparent depth bagiikan yang diperhatikanoleh Ahmad.

[2 marks]

5 (a) (i) Refraction of light [1 mark]

30o

(ii) Light that travels from a medium that is denser to less dense will be refracted away from the normal. But light always enters the human eyes in straight lines. Hence, it seems the light comes from a place nearer to the surface of the water.

[3 marks]

(iii) Using Figure above, draw the ray diagram that shows the formation of the fish image in the water.Denganmenggunakan Rajah di atas, lukiskan rajah sinar yang menunjukkanpembentukanimejikandalam air.

[2 marks]

(b) n = D/dd = D/n = 3/1.33 = 2.26 cm

[2 marks]

6. Diagram below shows light ray P directed into a glass block at an angle of 30o. The refractive index of the glass block is 1.71 and the speed of light in air is 3 x 108 ms-1.

(a) What is meant by refraction of light? [1 mark]

(b) Calculate the angle of refraction, r of the glass block. [2 marks]

(c) In Diagram above, complete the light ray for the glass block. Label the angle of refraction, r.(lukisgarisancahaya yang terbiaskeluardariprisma, mestilukiskangarisan normaldansudutr)

[3 marks]

(d) Find the critical angle, c of the glass block. [2 marks]

6 (a) The bending of a light ray at the boundary of two media as the light ray propagates from a medium to another.

[1 mark]

(b) sin r = sin r / n = sin 30 /1.71 = 0.2924 R = 17 o

[2 marks]

(c) [3 marks]

(d) c = sin-1 (1/n) = sin -1 (1/1.71) = 35.8o [2 marks]

7 Diagram 7.1 and Diagram 7.2 show an identical pencil is immersed in the

Ray P

r

Diagram 7.1 Diagram 7.2

Distilled waterSea waterAir laut

PencilPensil

distilled water and sea water respectively.Rajah 7.1 dan Rajah 7.2 menunjukkansebatangpensil yang serupamasing-masingditenggelamkan di dalam air sulingdan air laut

(a) Based on Diagram 7.1 and Diagram 7.2,Berdasarkan Rajah 7.1 dan7.2

[1 mark](i) compare the bending of the pencil

bandingkanpembengkokkanpensil[1 mark]

(ii) compare the density of distilled water and the sea water bandingkanketumpatan air sulingdan air laut

[1 mark](iii) state the relationship between the density of water with the bending of the pencil

nyatakanhubunganantaraketumpatan air denganpembengkokkanpensil.[1 mark]

(b) Based on Diagram 7.1, compare the size of the observed pencil inside and outside the distilled water Berdasarkan Rajah 7.1, bandingkanpemerhatiansaiz pencil di dalamdan di luar air suling.

[1 mark](c) Name the phenomenon shown in Diagram 7.1 and Diagram 7.2

Namakanfenomena yangditunjukkandalam Rajah 7.1 dan Rajah 7.2.[1 mark]

(d) Underline the correct answer in the bracket to complete the sentence below. Phenomenon in (d) happens because of the change in (velocity, frequency) of the light.Garisjawapan yang betuldalamkurunganuntukmelengkapkanayat di bawah.Fenomenapada (d) berlakudisebabkanperubahanpada(halaju, frekuensi)cahaya.

[1 mark](e) Diagram 7.3 shows a coin in a beaker filled with water. In Diagram 7.3 ,draw a ray diagram

from a coin to the eye to show how the image of the coin is formed.Rajah 7.3 menunjukkansatuduitsyillingberadadalambikarberisi air.PadaRajah 7.3,lukisgambar rajah sinardariduitsyillingkematauntukmenunjukkanbagaimanaimejduitsyillingituterbentuk.

[2 marks]7 (a)(i) Pencil in Diagram 7.2 more bending/vice versa

(ii) Density of seawater is higher/ vice versa

(iii) The higher the density the greater the bending(b) The size of the pencil in the water is greater(c) Diffraction(d) velocity(e)

8 Diagram 8 shows an object, O with height 2 cm placed on the left side of a convex lens, X. The focal length of the convex lens is 10 cm. Rajah 8 menunjukkansatuobjek,Odenganketinggian 2 cm diletakkan di sebelahkirikantacembung,X. Panjangfokuskantacembunginiialah 10 cm.

(a) In Diagram 8 draw the ray path from the object to form an image. Pada Rajah 8 lukiskanlintasansinardariobjekuntukmembentukimej.

[2 marks]

(b)

State the characteristics of the image formed. Nyatakanciri-ciriimej yang terbentuk.

[1 mark]

(c) If the object is placed at a distance 30 cm from the lens, calculate: Jikaobjekdiletakkanpadajarak 30 cm darikanta, hitung:

(i) the image distance. Jarakimej [2 marks]

(ii)

Linear magnification. Pembesaran linear. [1 mark]

(d)

You are given another convex lens, Y with power 2 Diopter. You are required to create a simple astronomical telescope using convex lenses X and Y. Andadiberisatukantacembungyang lain, Y dengankuasa 2 Diopter. Andadikehendakimerekasatuteleskopastronomiringkasmenggunakankedua-duakantacembung X dan Y.

(i) Which lens is suitable to be objective lens and eyepiece? Kantamanakah yang sesuaidijadikankantaobjekdankantamata?

Objective lens: ………………………………Kantaobjek

[2 marks]

Eyepiece : ………………………………Kantamata

(ii)

Give one reason to your answer in (d) (i). Berikanalasanbagijawapan di ( d) (i).

[1 mark]

(e) Draw the arrangement of the lenses and sketch the ray path from distance object using convex lenses X and Y to form a simple astronomical telescope. Lukiskansusunankantadanlakarkanlintasansinardarisatuobjekyangjauhdenganmenggunakankantacembung X dan Y untukmembentuksatuteleskopastronomiringkas.

[3 marks]

8 (a)

2

(b) Real, diminished, inverted 1

(c) (i) 1/f = 1/u +1/v v = 15 cm

2

(ii) m = v/u m = 0.5 1

(d) (i) Objective lens = convex lens Y

Eyepiece = convex lens X 2

(ii) Power of convex lens X > power of convex lens Y 1 (iii)

3

Total 12 9 (a) Diagram 9.1 shows a ray of light directed perpendicularly at a side of the semi-circular glass block.

The ray passes through the glass block to a point O before leaving the glass block. The angle of incidence in the glass block is 30°. Rajah 9.1 menunjukkansatubongkahkaca semi bulatan. Satusinarcahayaditujukansecarategakkesuatusisiblokkacaitu. Sinaritukemudiannyamemasukibongkahkacaitudanmenujuketitik O sebelumkeluarsemula. Suduttujusinaritu di dalamkacaadalah 30°.

semi circular glass block blokkaca semi bulatan

Diagram 9.1 Rajah 9.1

(i) What is meant by angle of incidence? Apakha yangdimaksudkandengansuduttuju? [1 mark]

(ii) Explain how total internal reflection occurs in Diagram 9.1 above? Terangkanbagaimanapantulandalampenuhberlaku didalam Rajah 9.1 di atas? [5 marks]

(b) Diagram 9.2 and Diagram 9.3 show two rectangular glass blocks with different optical density and refractive index. Ray of light is directed toward the glass blocks with the same angle of incidence 30°. Rajah 9.2 dan Rajah 9.3 menunjukkanduabuahbongkahkaca yang berlainanketumpatandanindeksbiasannya. Sinarcahayaditujukankepadakedua-duabongkahkacaitudengansuduttuju 30°.

Density = 2600 kgm-3Density = 2670 kgm-3

Ketumpatan = 2600 kgm-3ketumpatan = 2670 kgm-3

Diagram 9.2 Diagram 9.3 Rajah 9.2 Rajah 9.3 Based on Diagram 9.2 and Diagram 9.3, Berdasarkan Rajah 9.2 dan Rajah 9.3,

(i) compare the densities of the glass blocks. bandingkanketumpatanbongkahkacaitu.

[1 mark](ii) compare the refractive index of the glass blocks bandingkanindeksbiasanbongkahkacaitu.

[1 mark](iii) compare the angle of refraction of the glass blocks

bandingkansuduttujupembiasanbongkahkacaitu. [1 mark]

(iv) relate the angle of refraction, r and the density of the glass blocks. hubungkaitkansudutpembiasan,rdenganketumpatanblokkaca.

[1 mark](v) relate the angle of refraction, r and the refractive index of the glass blocks

hubungkaitkansudutpembiasan,rdenganindeksbiasankaca.[1 mark]

(c) Diagram 9. 4 shows a fibre optic. Rajah 9 .4 menunjukkan gentian optik.

You are required to give suggestions to design a fibre optics which can works efficiently. Using your knowledge on light, and the properties of material, explain the suggestion based on the following aspects; Andadimintauntukmemberikancadanganuntukmerekabentuksatu gentian optik yang dapatberfungsidengancekap. Menggunakanpengetahuanandatentangcahayadansifatbahan, terangkancadanganandaberdasarkanaspekberikut;

(i) the refractive index of outer and inner layer indeksbiasanlapisanluardandalam

(ii) flexibility kelenturan

(iii) strength kekuatan

(iv) thickness ketebalan

(v) density of the glass ketumpatankaca[10 marks]

9 (a) (i) Angle between incident ray and normal line 1

(ii) • Increase the angle of incidence i, then angle of refraction r will also increase

• Keep on increasing the angle of incidence until angle of refraction is 90°

• The angle of incidence is called critical angle

• Increase the angle of incidence more than the critical angle

• The ray will be reflected.

1

1 1

1

1

4/5

(b) • Density diagram 9.2 < density diagram 9.3 • Refractive index 9.2 < Refractive index 9.3 • Angle of refraction in diagram 9.2 > angle of refraction in diagram 9.3

• The higher the density the smaller the angle of refraction

• The higher the refractive index the smaller the angle of refraction.

1 1

1 1

1

Suggestion ExplanationUse refractive index of outerlayer is less than the refractive index of outer layer

So that total internal reflection can happen in the fiber optic.

Use high flexibility material so that it can be bendUse strong material do not break easilyUse thin material Lighter // can be use in small areaLow density material Lighter

Total 20