CENTRE FOR FOUNDATION STUDIES

Foundation in Science

January 2013 Intake

Mid Semester Examination

FSC 1106 Physics 2

Session : Morning November 2013 Duration : 2 hours

Instruction to Candidates:

1. Please check that this examination paper consists of seven (7) pages of printed material including the cover page before you begin the examination.

2. Answer questions in Part A , Part B and Part C in the answer booklet provided.

3. Non-programmable electronic calculators may be used.

4. You are not allowed to remove this question paper from the examination venue.

Name

Matric Number

Name of Lecturer

Exam Date Exam Time

Part A ( 10 marks)

Multi – choice Questions

Answer ALL Questions

1. Which one of the following waves cannot pass through a vaccum?

A Light C X-Rays

B Sound D radio waves

2. The basic difference between transverse and longitudinal waves is their ___________.

A wavelength C direction of motion

B frequencies D direction of vibration

3. The sound of an organ closed at one end has an effective distance of 0.40 m. Given that the speed of sound in air is 340 ms-1, the two lowest frequencies are ________________.

A 212.5 Hz and 283.3 Hz

B 212.5 Hz and 637.5 Hz

C 283.3 Hz and 637.5 Hz

D 283.3 Hz and 1333 Hz

4. A pipe open at both ends has an effective length of 0.20 m. If the speed of sound is 330 ms-1 , find the fundamental frequency of the pipe.

A 330 Hz C 1650 Hz

B 825 Hz D 3330 Hz

5. An object is placed in front of a thin convex lens with a focal length of f. The image produced is inverted and is half of the size of the object. The object distance is ___________.

A12

f C 2f

B13

f D 3f

6. An object is placed at a distance 10 cm in front a convex lens. If a real image is produced at a distance of 50 cm from the object, what is the focal length of the lens?

A 8.0 cm C 12.5 cm

B 8.3 cm D 13.3 cm

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7. Light in air is incident at an angle of 350 on a piece of crown glass with index of refraction of

1.52. What is the angle of refraction in the glass?

A 22.2o C 35o

B 30.5o D 40.3o

8. Refraction is involved in the following phenomena:

I mirage

II rainbow

III bending of a drinking straw in a glass of water

IV dispersion of light by a prism

A. III only

B. I & III only

C. I, II and III

D. I, II, III and IV

9. The intensity of a sound wave is 6 mW cm-2 . If the intensity level is increased by 10 dB, what is

the new intensity of the wave in mW cm-2 ?

A 6.06 C 12

B 6.6 D 60

10. A spherical sound wave is emitted by a point source. What is the intensity level of this sound at

5 m from the source compared to the intensity level at 1 m from the source?

A + 7 dB C + 14 dB

B - 7 dB D - 14 dB

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Part B (29 marks)

Structured Questions

Answer BOTH TWO (2) questions. Show your workings clearly in the answer booklet provided.

11. a) Name four regions of electromagnetic (EM) spectrum. [4 marks]

b) Which of them in 11(a) mentioned above has the highest frequency and lowest frequency? [2 marks]

c) Based on your answer in 11(a), give one example of application for each of the region. [4 marks]

12. a) i) State the laws of reflection. [2 marks]

ii) A 1.8 m tall shopper in a department store is 5.8 m from a convex security mirror. The shopper notices that his image appears to be only 16.3 cm tall.

Determine the radius of curvature of the mirror. [6 marks]

iii) Based on your answer in 12 (a)(ii), is the image upright or inverted? [2 marks]

b) A bi- convex lens has surfaces with radii of curvature 18 cm and 20 cm. When an object is placed 24 cm from the lens, a real image is

formed at 32 cm from the lens. i) Write the lens maker’s equation and explain the symbols used in the [3 marks] equation.

ii) Determine the focal length of the lens and the refractive index of the [6 marks] lens.

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Part C ( 25 marks)

Essay Questions

Answer ONE (1) question ONLY. The question is allocated with 25 marks. Show your workings

clearly in the answer booklet provided.

13. a) i) Briefly explain the meaning of resonance, threshold of hearing

and threshold of pain. [6 marks]

ii) Give two examples of resonance phenomena. [4 marks]

iii) Give three applications of sound waves. [6 marks]

b) i) Define Doppler effects. [3 marks]

ii) A boy was standing at a bus stop when the fire engine with velocity 40ms-1

emitting siren with frequency 550 Hz passed through him.

Calculate the frequency heard by the boy when it:

(a) is was approaching him

(b) is was moving away from him. [6 marks]

14. a) Briefly define sound intensity. [2 marks]

b) The overall length of a piccolo is 32.0 cm. The resonating air column

vibrates as in a pipe open at both ends. Calculate the frequency of the

lowest note a piccolo can play. [3 marks]

c) A variable length of air column is placed just below a vibrating wire that

is fixed at both ends. The length of the air column open at the end increased

until the first position of resonance is observed at 34.0 cm. The wire is

120 cm long and is vibrating in its third harmonic.

Calculate the speed of transverse waves in the wire. [4 marks]

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d) i) Briefly explain transverse and longitudinal waves? Provide an

example of each wave. [4 marks]

ii) The equation of a progressive wave is y = sin [ 3π (3x – 2t)] where

all the quantities are in SI units. Calculate the amplitude, wavelength [10 marks]

wave number, angular frequency and the wave velocity.

iii) State whether the wave in 14.d) ii) is moving towards positive or

negative direction. [2 marks]

---END OF PAPER---

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Formula Sheet

Speed of light in air or vacuum, c = 3.0 x 108 ms-1

Speed of sound in air, vs = 343 ms-1

Threshold of hearing, Io = 1.0 x 10-12 Wm-2

r = 2f

1u + 1

v = 1

f

m = - image distance , vobject distance ,u

n1 sin Ө1 = n2 sin Ө2

y( x,t) = A sin (ωt ± kx)

fo = V (air)

V ( air ) ±Vsfs

f0 = V ( air ) ±Vo

V (air) fs

λ = 2L

fo = vλ

fn = nfo

L= 14

λo

fopen = n v

2 L

fclosed = n v

4 L

B= 10 log ( I/ Io)

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