GameChanger Academy

Mechanics

1. Units, Dimensions and Errors

2. Vectors and Scalars

3. Motion in a Straight Line

4. Projectile Motion

5. Newton's Laws of Motion

6. Friction

7. Work, Energy, Power and Collision

8. Circular motion

9. Rotational motion

10. Simple Harmonic Motion

11. Gravitation

12. Elasticity

13. Surface Tension

14. Fluid dynamics and Viscosity

15. Hydrostatics

Heat and Thermodynamics

16. Thermometry

17. Thermal expansion

18. Calorimetry, Change of State and Hygrometry

19. Gas Laws and Kinetic theory of Gases

20. Transmission of Heat

21. Thermodynamics

Sound and Waves

22. Wave

23. Superposition of Waves

24. Stationary/ Standing waves

25. Doppler's effect and Musical sound

Optics

26. Reflection of Plane and Curved Mirrors

27. Refraction at Plane surfaces and Total internal reflection

28. Refraction through prism and Dispersion of Light

29. Refraction through Lenses

30. Chromatic abberation in Lenses, Optical instruments and Human eye

31. Velocity of Light

32. Photometry

33. Wave nature of Light

Electrostatics

34. Charge and Force

35. Electric Field and Potential

36. Capacitance

Electrodynamics

37. Electric current

38. Heating Effect of Current

39. Thermoelectricity

40. Chemical effect of Current

41. Meters

Electromagnetism

42. Properties of Magnets

43. Magnetic effects of Current

44. Electromagnetic induction

45. Alternating current

Modern Physics

46. Cathode rays, Positive rays and Electrons

47. Photoelectric effect

48. X-rays

49. Atomic structure and Spectrum

50. Radioactivity

51. Nuclear physics

52. Semiconductor and Semiconductor devices

53. Diode and Triode valves

54. Logic gates

55. Relativity and Universe

56. Particle physics

Sound and Waves

25. Doppler's effect and Musical sound

1. The driver of a car travelling with speed of 45 km/hr towards a person is also travelling by car towards source with same speed, the frequency of sound heard by person is provided that the driver's car produces frequency of 500 Hz:

[BP 2014]

500 Hz
540 Hz
600 Hz
640 Hz

2. Which can produce maximum pitch sound?

[BP 2013]

Lion
Man
Woman
Mosquito

3. The loudness of sound is 40 dB. What is the intensity level of sound?

[BP 2013]

10^-8 W/m²
10^-10 W/m²
10^-12 W/m²
10^-14 W/m²

4. A window whose area is 2 m² opens on a street where the street noise result in an intensity level at the window of 60 dB. How much 'acoustic power' enters the window via sound waves.

[BP 2009]

2 µW
4.5 µW
6 µW
8.5 µW

5. A source and listener is moving in the same direction with a velocity equal to half the velocity of sound what is the change in frequency.

[IOM 2013]

0%
100%
25%
50%

6. A car travels at a speed of 20 m/s towards a high wall. The driver sounds a horn of frequency 124 Hz. If velocity of sound in air is 330 m/s, the frequency of the reflected sound heard by the driver will be:

[MOE 2013]

109 Hz
140 Hz
149 Hz
280 Hz

7. A listener is moving away from stationary source of sound. The listener hears a sound of frequency:

[KU 2012]

Higher than the source frequency.
Lower than the source frequency.
Same as that of the source frequency.
Either (a) or (c).

8. A sound wave has intensity 10^-3 W/m². The intensity level in dB is equal to:

[KU 2012]

30 dB
0 dB
90 dB
120 dB

9. Which of the following sounds have maximum speed in air, sound produced by an explosion of a bomb, the roaring of a lion, buzzing sound of mosquito?

[BP 2013]

Sound produced by an explosion of a bomb
The roaring of a lion
The buzzing sound of mosquito
All above have equal speed

10. The notes that are separated by three octaves have a frequency ratio of:

[BP 2014]

11. A star is moving away from the earth. The wavelength of the light notes by the observer on the earth will be:

[BP 2015]

equal to the real wavelength
less than the real wavelength
more than the real wavelength
Doppler's effect is not applicable for light waves

12. The intensity level due to waves of same frequency in a given medium are 1 bel and 5 bel. Then the ratio of their amplitudes is:

[MOE 2011]

1:4
1:2
1:10
1:10²

13. A man is watching two trains, one leaving and the other coming towards him with equal speed of 4 m/s. If they sound their whistles, each of natural frequency of 240 Hz, the number of beats heard by (velocity of sound in air = 320 m/s) will be equal to:

[IOM 2014]

6
3
zero
12

14. Speed of sound in air at a given temperature is 350 m/s. An engine which blows horn of 1200 Hz, is approaching the observer with velocity 50 m/s. The apparent frequency as heard by the observer will be:

[MOE 2013]

600 Hz
1050 Hz
1400 Hz
2400 Hz

15. The apparent frequency noted by a moving listener away from the stationary source is 10% less than the real frequency. If the velocity of sound is 330 m/s, the velocity of the listener is:

[KU 2010]

16.5 m/s
8.25 m/s
33 m/s
66 m/s

16. A source of sound moves towards a stationary observer with a velocity equal to velocity of sound. If the source produces n waves/sec, the observer receives:

[BP 2012]

n waves/sec
2n waves/sec
n/2 waves/sec
all waves in no time

17. A tuning fork of frequency 90 Hz is sounded forward an observer moving with a velocity equal to 1/10th the velocity of sound. The note heard by the observer will have a frequency:

[MOE 2009]

100 Hz
90 Hz
99 Hz
990 Hz

18. A whistle is whirled in a circle of radius 1m and traverses the circular path twice per second. An observer is situated outside the circle but in its plane. If the velocity of sound is 332 m/s, then the interval between the highest and the lowest observed pitch is:

[IOM 2015]

332:1
332:47
2:1
1:1

19. A source of sound is moving with a velocity 50 m/s towards a stationary observer. The observer measures the frequency of the source as 1000 Hz. What will be the apparent frequency of the source when it is moving away from the observer after crossing him? (velocity of sound is 350 m/s in air)

[BPKIHS 2011]

750 Hz
875 Hz
1143 Hz
1333 Hz

20. A whistle giving out sound of frequency 450 Hz approaches a stationary observer at a speed of 33 m/s. The frequency heard by the observer is:

[MOE 2010]

400 Hz
429 Hz
517 Hz
500 Hz

21. The musical interval between two notes of frequencies 320 Hz and 240 Hz is:

[BP 2013]

80
1.33
1.7
7

22. The apparent wavelength of the light from a star moving away from the earth is 0.4% more than its real wavelength. The velocity of the star is:

[IOM 2016]

150 km/sec
15 km/sec
120 km/sec
30 km/sec

23. The intensity level of two waves of same frequency in a given medium are 20 dB and 60 dB. Then the ratio of their amplitudes is:

[KU 2012]

1:4
1:16
1:10²
1:100

24. A source of sound is moving away from a stationary observer with a speed equal to the speed of sound. The apparent frequency heard by the observer will be:

[KU 2010]

2n
n
n/2
None

25. A whistle giving out 450Hz approaches a stationary observer at a speed of 33 m/s. The frequency heard by the observer in Hz is:

[MOE 2010]

409 Hz
500 Hz
450 Hz
550 Hz

26. A radar sends a signal of frequency 7.8 × 10⁹/s towards an aeroplane moving with certain velocity. A frequency difference of 2.7 × 10³/s is reflected from the aeroplane. Find the velocity of the aeroplane.

[IOM 2007]

1.87 × 10² km/hr
2.87 × 10² km/hr
0.87 × 10² km/hr
3.74 × 10² km/hr

27. When air space in a musical instrument is increased, what will increase?

[IOM 1997]

pitch
loudness
quality
timbre

28. By which process, radio waves can be detected but not light waves in a closed room?

[MOE 2063/KU 08/09]

interference
reflection
diffraction
refraction

29. Quality of two sounds is different because:

[MOE 2062]

frequencies are different
Their intensities are different
Their amplitudes are different
Different overtones are present in them

30. The intensity of sound gets reduced by 10% on passing through a block. If it passes through two such blocks, the intensity of the outgoing sound is:

[MOE 2009]

31. The loudness of two waves of same frequency in a given medium are 100dB & 20 dB respectively. How many times is the intensity of I₁ is greater than I₂?

[IE 2005]

10²
10⁴
10⁵
10⁸

32. A car is slowly moving towards a wall with velocity 2 m/s. If the frequency of horn blow by car is 700Hz, then no. of beats heard by the driver is (velocity of sound = 350 m/s):

[BPKIHS 2015]

4 Hz
8 Hz
12 Hz
16 Hz

33. A policeman sounds a whistle with frequency 300 Hz towards a car that moves towards him with a velocity of 5 m/s. Find the frequency of the whistle as heard by the driver of the car. (Velocity of sound in air = 320 m/s):

[ITE 2010]

310 Hz
305 Hz
312 Hz
320 Hz

34. A man in a car moving at 40 m/s is approaching a stationary siren emitting a sound frequency 510 Hz. The apparent frequency heard by the man is (take velocity of sound = 300 m/s):

[BPKIHS 2007]

570 Hz
540 Hz
500 Hz
480 Hz

35. A bus is moving towards a huge wall with a velocity of 5 m/s. The driver sounds a horn of frequency 200 Hz. The frequency of the beats heard by a passenger of the bus will be (speed of sound in air = 350 m/s):

[BPKIHS 1996]

203 Hz
100 Hz
209 Hz
35 Hz

36. The intensity of sound gets reduced by 10% on passing through a slab. The reduction in intensity on passing through two consecutive slabs would be:

[MOE 2008]

37. The driver of a car sounds a horn of frequency 600 Hz moving towards the hill with a speed 30 m/s. If speed of sound in air is 330 m/s, then frequency received by driver after reflection from hill is:

[BPKIHS 2014]

650 Hz
680 Hz
720 Hz
750 Hz

38. A man is watching two trains, one is leaving and the other is coming towards him with equal speed of 4 m/s. If they sound their whistles, each of natural frequency of 240 Hz, the number of beats heard by the man (velocity of sound in air = 320 m/s) will be:

[MOE 2012]

6 Hz
3 Hz
0 Hz
12 Hz

39. An object producing a pitch of 400 Hz approaches a stationary person in a straight line with a velocity of 200 m/s. Velocity of sound is 300 m/s. The person will note a change in frequency as the object flies past him equal to:

[IOM 2015]

1440 Hz
240 Hz
1200 Hz
960 Hz

40. A beam of sound is 10⁶ times as intense as that with minimum audible intensity. The loudness of the beam is thus:

[BP 2011]

10 dB
6 dB
60 dB
0.6 dB

41. An engine is moving on a circular track of radius 100 m with the speed of 20 m/s. What will be the frequency observed by an observer standing stationary at the centre of the circular path when the engine blows a whistle of frequency 500 Hz?

[IOM 2016]

> 500 Hz
< 500 Hz
500 Hz
No sound

42. When both source and observer approach each other with a velocity equal to half of the velocity of sound, the change in frequency of sound as detected by the listener is:

[MOE 2014]

0
200%
50%
150%

43. A source of sound produces waves of λ = 40 cm in air. It is moving with a velocity one-fourth the velocity of sound towards east. The apparent wavelength noted by a man in opposite direction is:

[BP 2010]

30 cm
60 cm
50 cm
70 cm

44. At what speed should a source of sound move so that observer finds the apparent frequency equal to half of the original frequency:

[KU 2011]

45. A galaxy is approaching the earth with a velocity of 10⁵ m/s. As observed on the earth, the shift in the spectral line of wavelength 5700 Å will be:

[IOM 2017]

1.9 Å
0.19 Å
0.53 Å
1.06 Å

46. Two whistles A and B produce notes of frequencies 600 Hz and 596 Hz respectively. There is a listener at the middle of the line joining them. Now the whistle B and the listener start moving with the speed 30 m/s away from the whistle A. If the speed of the sound is 330 m/s, how many beats will be heard by the listener?

[BP 2016]

47. A whistle of frequency 500 Hz is tied to a end of a string of length 1.2 m revolves at 400 rev/min. A listener standing some distance away in the plane of rotation of whistle hears frequencies in the range: (speed of sound = 340 m/s):

[MOE 2015]

436 to 574 Hz
426 to 586 Hz
426 to 574 Hz
436 to 586 Hz

48. In the spectrum of light of a luminous heavenly body, the wavelength of spectral line is measured to be 4747 Å while actual wavelength of the spectral line is 4700 Å. Then relative velocity of heavenly body w.r.t earth is:

[IOM 2018]

3 × 10⁵ m/s, moving towards the earth
3 × 10⁵ m/s, moving away from the earth
3 × 10⁶ m/s, moving towards the earth
3 × 10⁶ m/s, moving away from the earth

49. The wavelength of light observed on the earth, from a moving star is found to decrease by 0.05% relative to the earth, the star is:

[BPKIHS 2017]

moving away with a velocity of 15 × 10⁴ m/s
coming closer with a velocity of 15 × 10⁴ m/s
moving away with a velocity of 1.5 × 10⁴ m/s
coming closer with a velocity of 15 × 10³ m/s

50. An astronaut in a rocket approaching towards the moon sends a radio wave of frequency 5 × 10⁹ Hz towards the moon. The frequency received by him is 9 × 10⁶ Hz more than the actual frequency. Then relative velocity of rocket w.r.t moon is:

[IOM 2019]

1.35 km/s
2.70 km/s
4.05 km/s
5.4 km/s

51. Two cars are moving on two perpendicular roads towards a crossing with uniform speeds of 72 km/h and 36 km/h. If the first car blows a horn of frequency 280 Hz, then the frequency of the horn heard by the driver of the second car when line joining the car makes an angle of 45° with roads will be:

[MOE 2016]

321 Hz
298 Hz
289 Hz
280 Hz

52. A source of sound emits 200 μW power which is uniformly distributed over a sphere of radius 10 m. What is the loudness of sound on the surface of the sphere? (log₁₀2 = 0.3):

[BP 2017]

200π dB
120π dB
140π dB
117 dB

53. A person is standing on a railway station. When a train is approaching him, the frequency of whistle heard by him is 220 Hz, but when the train has crossed him, the frequency heard by him is 184 Hz. The actual frequency of the whistle is:

[BPKIHS 2015]

200 Hz
202 Hz
207 Hz
√(184 × 220) Hz

54. A person is driving in a car with velocity 30 m/s towards the rock. The person honked the car with frequency 600 Hz & the sound is reflected from rock. The apparent frequency heard by the person is? [velocity of sound 330 m/s]:

[IOM 2016]

555.5 Hz
550 Hz
610 Hz
720 Hz

55. Stationary observer heard twice the original frequency of the source moving towards the observer. What is the velocity of source? [Given the velocity of sound 332 m/s]:

[IOM 2016]

99 m/s
166 m/s
272 m/s
332 m/s

56. A sound having intensity of 10^-4 W/m² has loudness of:

[KU 2017]

60 dB
30 dB
90 dB
120 dB

57. When both source and observer moving in the same direction with the velocity half that of sound. Then the percentage of increase in frequency will be:

[IOM 2017]

0%
50%
100%
200%