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

Heat and Thermodynamics

20. Transmission of Heat

1. According to Wien's displacement law, maximum wavelength of emission is related to temperature as:

[BP 2011]

λ_max ∝ T
λ_max ∝ T^-1
λ_max ∝ T^1/2
λ_max ∝ T^-1/2

2. Body cools from 50°C to 49.9°C in 5s (surrounding=30°C). Time to cool from 40°C to 39.9°C?

[BP 2010]

3. Which can be considered a black body?

[BP 2010]

Metallic sphere with fine opening
Sodium vapor lamp
Intensely heated coal
Glass coated with lamp black

4. Two cylinders (same material) with diameter ratio 1:2 and length ratio 2:1. Heat conduction ratio?

[IOM 2012]

5. Heat energy by radiation is proportional to:

[IOM 2012]

T²
√T
T⁴
T³

6. Four colored articles (blue, red, black, white) heated then cooled. Which cools fastest?

[IOM 2011]

Blue
Red
Black
White

7. Object cools 80°C→70°C in 1min (room=30°C). Time for 50°C→40°C?

[MOE 2012]

2min
3min
4min
5min

8. Sun's λ_max at T₁,T₂,T₃ are 650nm,580nm,350nm. Correct relation?

[IOM 2010]

T₁>T₂;T₁>T₃
T₃>T₁;T₃>T₂
T₂>T₁;T₂>T₃
T₁=T₂=T₃

9. When ΔT=20°C, heat flow=273J/s. If ΔT becomes 20K, new heat flow?

[MOE 2009]

253 J/s
232 J/s
273 J/s
100 J/s

10. Ratio of energy emitted at 27°C and 600K?

[MOE 2010]

1/2
1/4
1/8
1/16

11. Stars A and B have λ_max at 3600Å and 4800Å. Temperature ratio T_A/T_B?

[MOE 2012]

3:4
4:3
256:81
81:256

12. Stars radiate max at 3200Å and 4000Å. Temperature ratio?

[MOE 2013]

4:5
5:4
25:16
2:5

13. Liquid cools from 60°C to 50°C in 5min (surrounding=18°C). Temperature after next 5min?

[MOE 2014]

28°C
22°C
24°C
26°C

14. Black body radiates at rate E at T. When T doubles, new radiation rate?

[KU 2013]

15. Rate of heat loss is:

[KU 2011]

∝ surface area
∝ (surface area)²
∝ 1/surface area
∝ 1/(surface area)²

16. Kirchhoff's law states:

[KU 2010-2014]

Good absorber = good emitter
Good absorber = poor emitter
Good emitter = poor absorber
Poor emitter = good absorber

17. Kirchhoff's law implies:

[KU 2013]

Good absorber = good reflector
Poor absorber = poor reflector
Good absorber = poor reflector
Poor absorber = good reflector

18. Two rods (K₁/K₂=5/3) joined end-to-end with ends at 100°C and 20°C. Junction temp?

[KU 2013]

70°C
80°C
60°C
90°C

19. Black spot on red-hot metal plate in dark room appears:

[KU 2014]

Red spot, black plate
White spot, red plate
White spot, black plate
Invisible spot, black plate

20. Refrigerator theory is based on:

[TE 2013]

Joule-Thomson effect
Newton's cooling
Kelvin-Planck statement
Celsius scale

21. If T halved, radiating power becomes:

[MOE 2009]

25%
12.5%
6.25%
3.125%

22. Correct emissive power relation:

[KU 2010]

E ∝ T
E ∝ T²
E ∝ T³
E ∝ T⁴

23. Best cooking pot material has:

[BP 2016]

Low c, high K
Low c, low K
High c, low K
High c, high K

24. Stars with λ_max=320nm and 400nm. Temperature ratio?

[IOM 2003]

5:4
4:5
2:5
4:25

25. Instrument measuring temperature by radiation:

[IOM 2000]

Pyrometer
Radiomicrometer
Thermometer
Barometer

26. Rate of heat loss depends on:

[IOM 1998]

Body temperature
Excess over surrounding
Thermal capacity
Surrounding temperature

27. Two black bodies at T and T' emit λ_m and λ_m'. Correct ratio?

[MOE Curriculum]

λ_m/λ_m' ∝ T/T'
λ_m/λ_m' ∝ T'/T
λ_m/λ_m' ∝ (T/T')²
λ_m/λ_m' ∝ (T'/T)²

28. Sun/Moon λ_max ratio=1:400. Temperature ratio?

[MOE 2008]

200:1
400:1
1:200
1:400

29. Unit of thermal conductivity:

[MOE 2005]

W m^-1 K^-1
J s^-1 K^-1
W K^-1 m^-1
J s K^-1

30. If T increases 50%, radiation increase %:

[MOE 2006]

50%
100%
500%
400%

31. Water's thermal expansion coefficient at 0°C:

[Bangladesh Embassy]

Positive
Negative
Zero
Infinite

32. If T doubles, radiated energy increases by factor:

[Bangladesh 2009]

33. Black body at 27°C vs 127°C radiation ratio:

[TE-2004]

9:16
27:64
81:256
3:4

34. Polished metal pot minimizes heat loss by:

[IE-2005]

Preventing convection
Reducing radiation
Preventing conduction
Saving material

35. Hot sand sensation due to:

[TE-2005]

Low specific heat
High specific heat
Radiation
Convection

36. Heat loss rate at 288K (σ=5.67×10^-8 W/m²K⁴):

[]

390 W/m²
288 W/m²
450 W/m²
250 W/m²

37. Pond heating occurs mainly by:

[]

Conduction
Convection
Radiation
All

38. Which rod conducts most heat? (r=radius, l=length)

[]

r=1cm, l=1m
r=2cm, l=2m
r=1cm, l=2m
r=2cm, l=1m

39. To radiate 16× power, temperature change:

[]

T₂=16T₁
T₂=8T₁
T₂=4T₁
T₂=2T₁

40. Two spheres (r=1m@4000K vs r=4m@2000K):

[]

1st radiates more
2nd radiates more
Equal
Can't determine

41. Two rods (K=2 and 3) in series. Equivalent K?

[]

1.0
2.0
3.0
None

42. Rod AB (150cm) with T_A=100°C, T_B=25°C. Temp at 50cm from B?

[]

50°C
60°C
75°C
80°C

43. Two-layer slab (K₁, K₂) of equal thickness. Equivalent K?

[]

K₁+K₂
2K₁K₂/(K₁+K₂)
(K₁+K₂)/2
K₁K₂

44. Two walls (d₁,K₁ and d₂,K₂) in contact. Interface temp?

[]

(K₁T₁+K₂T₂)/(K₁+K₂)
(K₁T₁d₂+K₂T₂d₁)/(K₁d₂+K₂d₁)
(K₁d₁+K₂d₂)(T₁T₂)/(T₁+T₂)
(K₁d₁T₁+K₂d₂T₂)/(K₁d₁+K₂d₂)

45. Metallic rod radiates 10W at 77°C. Radiation at 227°C?

[]

(227/77)×10W
(227/77)²×10W
42W
160W

46. Wall with layers A (3K) and B (K) of equal thickness. ΔT across A?

[]

6°C
9°C
12°C
27°C

47. Composite rod of materials K₁ and K₂. Equivalent K?

[]

2(K₁+K₂)
(K₁+K₂)/2
K₁+K₂
K₁K₂/(K₁+K₂)

48. Wall with layer A (2K) and B (K). Total ΔT=36°C. ΔT across A?

[]

6°C
36°C
24°C
12°C

49. Sphere cooling rate depends on:

[]

rρc
1/rρc
3rρc
1/r²ρc

50. Two spheres (R₁, R₂) of same material cool under identical conditions. Rate ratio?

[]

R₂:R₁
R₁:R₂
R₁²:R₂²
R₂²:R₁²

51. Two identical rods: series vs parallel K_eq?

[]

K_eq_series = K_eq_parallel
K_eq_series > K_eq_parallel
K_eq_series < K_eq_parallel
None

52. Equal ΔT across two rods. Equal heat transfer when:

[]

K₁A₂ = K₂A₁
K₁A₂ = K₂A₁²
K₁A₁ = K₂A₂
K₁A₁² = K₂A₂²

53. Sphere, cube, and plate (same material/mass) heated to 200°C. Which cools slowest?

[]

Sphere
Cube
Plate
All same

54. Two cylinders (diameters d₁, d₂) conduct equal heat when lengths relate as:

[]

L₁/L₂ = d₁/d₂
L₁/L₂ = (d₁/d₂)²
L₁/L₂ = d₂/d₁
L₁/L₂ = (d₂/d₁)²

55. Two spheres (big: 2r, t/4 vs small: r, t). Ice melts in 25min vs 16min. K_big/K_small?

[]

4:5
5:4
25:8
8:25

56. Body cools 50°C→40°C in 10min (surrounding=20°C). Next 10min temp?

[]

35°C
33.3°C
32°C
30°C

57. Tea cools 80°C→60°C in 1min (ambient=30°C). Time for 60°C→50°C?

[IOM 2015]

58. Body cools 60°C→50°C in 10min (room=25°C). Next 10min temp?

[]

38.5°C
40°C
42.85°C
45°C

59. Cooling times t₁(100→80°C), t₂(80→60°C), t₃(60→40°C) with T_∞=27°C:

[]

t₁=t₂=t₃
t₁23
t₁>t₂>t₃
t₂>t₁>t₃

60. Liquid loses 60cal/s at 80°C (room=20°C). Heat loss at 40°C?

[]

180cal/s
40cal/s
30cal/s
20cal/s

61. 1cm Cu cube cools 100→99°C in 100s. 2cm cube cooling time?

[]

25s
50s
200s
400s

62. Black body at 2880K. U₁(499-500nm), U₂(999-1000nm), U₃(1499-1500nm):

[]

U₁=0
U₃=0
U₁>U₂
U₂>U₁

63. Ice forms 1cm in 7h at -10°C. Time for 1→2cm?

[]

64. Body cools 65→60°C in 5min. Time for 60→55°C?

[IOM 2010]

5min
<5min
>5min
Depends on mass

65. If ΔT doubles, thermal conductivity:

[KU 2015]

Halves
Doubles
Unchanged
4×

66. Heat transfer by particle movement:

[IOM 2015]

Conduction
Convection
Reflection
Radiation

67. Newton's cooling applies to:

[IOM 2017]

Gas latent heat
Gas specific heat
Liquid specific heat
Liquid melting point

68. Greenhouse effect caused by:

[KU 2016]

Infrared
UV
X-ray
Visible