ECAT Physics Modern Physics Test Online

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Question 1

1. Mark the wrong statement:

Answer

A frame of reference which is either at rest or moves with a constant velocity is called an inertial frame of reference

Answer

An un-accelerated frame of reference is called an inertial frame of reference

Answer

All the frames of reference in uniform rectilinear motion are equivalent

Answer

Newton’s laws of motion are valid in an accelerated (non inertial) frame of reference

Question 2

2. In translatory motion, the axes of the frame of reference of the object remains always parallel to the corresponding axes of?

Answer

Observer’s frame of reference

Answer

Mover’s frame of reference

Answer

Rotator’s frame of reference

Answer

None of these

Question 3

3. Inertial frame of reference is that

Answer

Which has large inertia

Answer

Which has no inertia

Answer

In which Newton’s first law of motion is applicable

Answer

None of these

Question 4

4. Special theory of relativity treats problems involving

Answer

Inertial frame of reference

Answer

Non-inertial frame of reference

Answer

Non-accelerated frame of reference

Answer

Accelerated frame of reference

Question 5

5. An observer shoots parallel to a meter stick at very high (relativistic) speed and finds that the length of meter stick is

Answer

Greater than one meter

Answer

Less than one meter

Answer

A foolish question

Question 6

6. According to special theory of relativity, speed of light in a vacuum

Answer

Is high for observers moving towards its source

Answer

Is high for observers moving away from its source

Answer

Same for all the observers in relative motion with respect to each other

Answer

Depends upon the uniform transnational motion of the source of light with respect to the observer

Question 7

7. According to special theory of relativity, mass of an object moving relative to an observer with a velocity comparable to the velocity of light

Answer

Remain constant

Answer

None of these

Question 8

8. According to Einstein special theory of relativity the mass of a particle moving with speed of light will be

Question 9

9. Time interval between two events as recorder by an observer in relative motion with velocity comparable velocity of light with respect to the point of occurrence of the event.

Answer

Remains constant

Answer

None of these

Question 10

10. With increase in the velocity of an object its mass will continuously

Answer

Remain constant

Answer

None of these

Question 11

11. According to special theory of relativity which one is not an absolute quantity?

Answer

Both A and B

Question 12

12. Length contraction happens only

Answer

Along the direction of motion

Answer

Parallel to direction of motion

Answer

Both A and B

Answer

None of these

Question 13

13. The phenomenon of black body radiations can be explained on the basis of

Answer

Wave theory

Answer

Classical theory

Answer

Bohr’s theory

Answer

Quantum theory

Question 14

14. The S.I unit of plank’s constant is

Answer

Joule per sec

Answer

Joule per sec²

Answer

Joule — sec

Answer

Joule per sec³

Question 15

15. A hot body will radiate maximum energy it its surface is

Answer

White and polished

Answer

Black and polished

Answer

White and rough

Answer

Black and rough

Question 16

16. The S.I. unit of Stefan’s constant is

Answer

W/m² K⁴

Answer

J/m s K⁴

Answer

N/m² K⁴

Answer

J/m² K⁴

Question 17

17. Which of the following statements is wrong?

Answer

Stefan’s constant is the same for all black bodies

Answer

Thermal radiation travel with the speed of 3 x 10⁵ m/s

Answer

Thermal radiation exhibit diffraction

Answer

Stefan’s law is applicable for all heated bodies

Question 18

18. As the temperature of black body is raised the wavelength corresponding to maximum intensity

Answer

Shifts towards loner wavelength

Answer

Shifts towards shorter wavelength

Answer

Remain the same

Answer

Shifts towards longer as well as shorter wavelengths

Question 19

19. Stopping potential for a metal surface in case of photoelectric emission depends on

Answer

The threshold frequency for the metal surface

Answer

The intensity of incident light

Answer

The frequency of incident light and work function of the metal surface

Answer

All of these

Question 20

20. Tick the right statement

Answer

No photo electronic emission takes place if the frequency of radiation however intense it may be is less than a certain critical value called threshold frequency

Answer

Threshold frequency depends upon the nature of the metal surface

Answer

Maximum energy of a photoelectron is a function of frequency rather than intensity of radiation

Answer

All of these

Question 21

21. A device based on photoelectric effect is called

Answer

Photo sensitive detection

Answer

Photo diode

Answer

Photosynthesis

Answer

Photo cell

Question 22

22. In a photoelectric effect monochromatic light is incident on a metal surface. If incident light of twice the intensity but of same wavelength the kinetic energy of the emitted electron

Answer

Becomes double

Answer

Remains same

Answer

Becomes half

Answer

First increases then decreases because curvilinear graph

Question 23

23. If the wavelength of incident radiation is increased in photoemission then

Answer

The maximum kinetic energy of the photoelectrons increases

Answer

The minimum kinetic energy of the photoelectrons decreases

Answer

The minimum kinetic energy of the photoelectrons Increases

Answer

The average kinetic energy of the photoelectrons decreases

Question 24

24. When light of suitable frequency falls on the surface of a metal electrons are emitted from it, this phenomenon is known as

Answer

Compton effect

Answer

Thermionic emission

Answer

Photo multiplier effect

Answer

Photoelectric effect

Question 25

25. Minimum frequency required to initiate photoelectric effect is called

Answer

Minimum frequency

Answer

Maximum frequency

Answer

Threshold frequency

Answer

Quantum frequency

Question 26

26. The value of work function depends upon

Answer

Frequency of incident light

Answer

Wave length of incident light

Answer

Nature of metal surface

Answer

Time for which metal is exposed

Question 27

27. In photoelectric effect light exhibits

Answer

Wave nature

Answer

Particle nature

Answer

Neither wave nor particle nature

Answer

Particle as well as wave nature

Question 28

28. In Compton effect frequency of scattered photon is

Answer

Less than the frequency of incident photon

Answer

Greater than the frequency of incident photon

Answer

Equal to the frequency of incident photon

Answer

None of these

Question 29

29. The change in frequency of scattered photon depends upon the

Answer

Wave length of incident light

Answer

Angle at which photon collides with electron

Answer

Angle of scattering

Answer

Frequency of incident light

Question 30

30. The scattering of X — ray photo by an electron is called

Answer

Photoelectric effect

Answer

Scattering effect

Answer

Compton effect

Answer

Pair production

Question 31

31. Compton effect proves the

Answer

Photon theory of light

Answer

Dual nature of light

Answer

Wave nature of light

Answer

Uncertain nature of light

Question 32

32. The uncertainty in momentum & position is due to its

Answer

Property of matter and radiation

Answer

Two dimensional motion

Answer

Emission of certain wavelength

Answer

Very high velocity

Question 33

33. In Compton scattering the change in wave length is max if

Answer

Angle of scattering is 90?

Answer

Angle of scattering is 60?

Answer

Angle of scattering is 180?

Answer

Angle of scattering is zero?

Question 34

34. According to uncertainty principle, the product of uncertainties tp and Ax in the measurements of momentum and position respectively of a particle at a certain instant is of the order of

Answer

Plank’s constant

Answer

Rydberg constant

Answer

Joule’s constant

Answer

Stephan’s constant

Question 35

35. Compton effect is associated with

Answer

Positive rays

Question 36

36. The phenomenon of pair production is

Answer

Lionization of neutral atom,

Answer

The production of an electron and a positron from y —rays

Answer

Ejection of an electron from a metal surface when exposed to ultraviolet Light.

Answer

Ejection of and electron from a nucleus.

Question 37

37. De Broglie waves are associated with

Answer

Moving charged particles only

Answer

Moving neutral particles only

Answer

All moving particles

Answer

All particles whether in motion or at rest

Question 38

38. Every motion is

Answer

None of these

Question 39

39. Classical physics is still valid in

Answer

Very small particles

Answer

Fast moving particles

Answer

Ordinary process

Answer

None of these

Question 40

40. A frame of reference is any coordinate system to which measurements are taken as:

Answer

Specifically

Answer

None of these

Question 41

41. An accelerated from of reference is called

Answer

Inertial frame

Answer

None-inertial frame

Answer

Both a and b

Answer

None of these

Question 42

42. General theory of relativity is applicable in the

Answer

Inertial frame of reference

Answer

Non-inertial frame of reference

Answer

Both frames of reference

Answer

None of these

Question 43

43. Time dilation is the result of special theory of relativity in which

Answer

Time increases

Answer

Time decreases

Answer

Remains the same

Answer

None of these

Question 44

44. A body of some material capable of absorbing all heat radiation incident on it and can emit in turn all the radiation at constant temperature after it is in equilibrium with it is called

Answer

Black body

Answer

Black body radiation

Answer

Black body cavity

Answer

Cavity radiation

Question 45

45. Exact time can be measured in

Answer

Inertial frame

Answer

None-Inertial frame

Answer

Stationary frame

Answer

None of these

Question 46

46. Aging process of the human body is slowed by motion at

Answer

Very slow speed

Answer

Very high speed

Answer

Very high speed along a circular path

Answer

None of these

Question 47

47. Earth’s orbital speed is

Answer

20 kms¯¹

Answer

30 kms¯¹

Answer

40 kms¯¹

Answer

50 kms¯¹

Question 48

48. At low temperature, a body emits wavelength in the region of

Answer

Ultraviolet

Answer

Far-infra red

Answer

None of these

Question 49

49. The platinum wire is changes to cherry red at

Question 50

50. A body termed as black body when it

Answer

Reflects all radiations

Answer

Absorbs all radiations

Answer

Absorbs and radiates all radiations

Answer

None of these

Question 51

51. The relation λmax X T=Constant represents

Answer

Stepfen’s law

Answer

Planck’s law

Answer

Wein’s law

Answer

None of these

Question 52

52. A beam of monochromatic radiation falls on a metal and photoelectrons are emitted. The rate of emission of photoelectrons will be double if

Answer

A beam of double the intensity is used

Answer

Radiation of double the frequency is used

Answer

Radiation of double the wavelength is used

Answer

The temperature of the metal is doubled

Question 53

53. Max Planck received the Nobel Prize in Physics in

Answer

None of these

Question 54

54. The energy of photon of radio waves in only about

Answer

10¯⁶ eV

Answer

10¯⁴ eV

Answer

10¯¹⁰ eV

Answer

10¯¹² eV

Question 55

55. Photoelectric effect is the phenomenon is which electrons are emitted from the metal when

Answer

It is heated

Answer

Light falls

Answer

Electrons strikes

Answer

None of these

Question 56

56. The amount of energy needed to remove electrons from the metal surface depends upon

Answer

Work Function

Answer

Wavelength

Question 57

57. When scattered X-ray photons are observed at θ = 90°, the Compton shift ∆λ equal to

Answer

Compton shift

Answer

Compton wavelength

Answer

Full wavelength

Answer

None of these

Question 58

58. A phenomenon is which a low energy photon interact with metal and usually absorbed with the emission of an electron is known as

Answer

Compton effect

Answer

Pair production

Answer

Photoelectric effect

Answer

None of these

Question 59

59. A very high energy photon (ϒ-rays) interact with matter and changes into

Answer

Pair of electron and positron

Answer

None of these

Question 60

60. A positron is a particle having

Answer

Mass equal to electrons

Answer

Charge equal to electrons

Answer

Equal but opposite charge

Question 61

61. Light in short is the most refined form of

Answer

None of these

Question 62

62. The diffraction patterns can also been observed in Davisson and Germer experiment with

Answer

Hydrogen atoms

Answer

Helium atoms

Answer

All of these

Question 63

63. A 50 kV microscope gives the resolution of

Answer

0.4 to 2nm

Answer

0.3 to 3 nm

Answer

0.5 to 1 nm

Answer

None of these

Question 64

64. The angle of scattering for which the Compton shift is maximum

Answer 214

Electrical energy to light energy

Answer 215

Light energy to light energy

Answer 216

Light energy to electrical energy

Answer 217

Light energy to elastic energy

Answer 218

ϒ-rays have smaller wavelength than X-rays

Answer 219

ϒ-rays emanate from nucleus while X-rays emanate from outer part of the atom

Answer 220

ϒ-rays have greater ionizing power than X-rays

Answer 221

ϒ-rays are more penetrating than X-rays

Answer 222

Is equal in both cases

Answer 223

More when ultraviolet is used

Answer 224

More when infrared is used

Answer 225

May be more or less for ultraviolet depending upon its intensity as compared to the intensity of infrared light

Answer 226

Work function of the surface

Answer 227

Amount of photoelectric current

Answer 228

Stopping potential will be reduced

Answer 229

Maximum K.E. of photoelectron

Answer 230

Photoelectric current increases

Answer 231

Photoelectric current decreases

Answer 232

Kinetic energy of emitted photo electrons increases

Answer 233

Kinetic energy of emitted photo electrons decreases

Answer 234

The collision of electrons with the target atom due to transfer of momentum

Answer 235

The collision of electrons with the target atom due to transfer of energy

Answer 236

The transition of electrons of heavy target atoms from high to low energy level on striking with electrons

Answer 237

None of these

Answer 238

Will be monochromatic

Answer 239

Will have all possible wavelengths less than a certain longest wavelength

Answer 240

Will have all possible wavelengths greater than a certain shortest wavelength

Answer 241

Will have all wavelengths between the longest and the shortest wavelength

Answer 242

Equal in all cases

Answer 243

Radio waves

Answer 244

Cosmic rays

Answer 245

Phosphorescene

Answer 246

Fluorescence

Answer 247

Anodization

Answer 248

Breakage of discharge tube

Answer 249

None of these

Answer 250

Equal to speed of light

Answer 251

Greater than speed of light

Answer 252

Less than speed of light

Answer 253

May be less than, greater than or equal to speed of light

Answer 254

A cathode ray tube

Answer 255

A rectifier

Answer 256

An oscillator

Answer 257

A radio telescope

Answer 258

α-particle

Answer 259

Specific charge

Answer 260

Wavelength

Answer 261

Maximum KE of photoelectrons is just doubled

Answer 262

Maximum KE of photoelectrons remains same

Answer 263

Maximum KE will be more than doubled

Answer 264

Maximum KE is halved

Answer 265

Increasing the current in the filament

Answer 266

Decreasing the current in the filament

Answer 267

Increasing the potential difference between the cathode and the anode

Answer 268

Decreasing the potential difference between the cathode and anode

Answer 269

a > b, b > c

Answer 270

a < b, b > c

Answer 271

a < b, b < c

Answer 272

a > b, b < c

Answer 273

Would decrease

Answer 274

Would increase

Answer 275

Would remain the same

Answer 276

My increase or decrease depending on the polarization of light

Answer 277

An energetic neutron emitted by a nucleus

Answer 278

An energetic electron emitted by a nucleus

Answer 279

An energetic photon emitted by a nucleus

Answer 280

An energetic proton emitted by a nucleus

Answer 281

The intensity of incident light

Answer 282

The frequency of light

Answer 283

The wavelength of light

Answer 284

None of these

Answer 285

v = 2 v₀

Answer 286

Charge of electron

Answer 287

Mass of electron

Answer 288

Revolution of electron around the nucleus

Answer 289

Speed of electrons

Answer 290

Intensity of incident radiations

Answer 291

Frequency of incident radiations

Answer 292

Square of the frequency of incident radiations

Answer 293

Square of intensity of incident radiations

Answer 294

Frequency of incident radiations should be less than threshold frequency

Answer 295

Frequency of incident radiation may have any value

Answer 296

Weave length of incident radiation should be less than threshold wavelength

Answer 297

Wavelength of incident radiation may have any value

Answer 298

Wavelength of incident light

Answer 299

Frequency of incident light

Answer 300

Intensity of incident light

Answer 301

All of these

Answer 302

Photo-electric effect

Answer 303

Interference

Answer 304

Refraction

Answer 305

Polarization

Answer 306

Do not get deflected at all

Answer 307

Get deflected in the direction of the filed

Answer 308

Get deflected in the direction opposite to the filed

Answer 309

Get deflected in the direction perpendicular to the field

Answer 310

Reproduction of films from the cinema files

Answer 311

Reproduction of sound from the cinema films

Answer 312

Automatic switching of street light

Answer 313

Both B and C

Answer 314

Is a form of transverse wave

Answer 315

Is a form of longitudinal wave

Answer 316

Can be polarized

Answer 317

Consists of quanta

Answer 318

Intensity of incident light

Answer 319

Frequency of incident light

Answer 320

Both A and B

Answer 321

Neither A nor B

Answer 322

Compton effect

Answer 323

Raman effect

Answer 324

Pair production

Answer 325

Production of X-rays

Answer 326

Time is absolute

Answer 327

The speed of light in a vacuum, measured in all inertial reference frames always has the same value of c, no matter how fast the source of light and the observer are moving relative to each other

Answer 328

Space is absolute

Answer 329

At rest mass of an object is always zero

Answer 330

Special theory of relativity

Answer 331

Quantum theory

Answer 332

Corpuscular theory

Answer 333

Bohr’s theory

Answer 334

3 x 10⁸ ms¯¹

Answer 335

3 x 10⁸ cms¯¹

Answer 336

3 x 10⁸ ms¯²

Answer 337

3 x 10⁸ cms¯²

Answer 338

Light travels in the form of quanta of energy

Answer 339

Light travels in the form of transverse waves

Answer 340

Light travels in the form of longitudinal waves

Answer 341

Light is a transverse electromagnetic wave

Answer 342

Frequency of incident light

Answer 343

Wavelength

Answer 344

Both Particles and Waves

Answer 345

None of these

Answer 346

Annihilation

Answer 347

Pair production

Answer 348

Compton Effect

Answer 349

Photoelectric Effect

Answer 350

Pauli’s Exclusion Principle

Answer 351

Heisenberg Uncertainty

Answer 352

Photoelectric Effect

Answer 353

Compton Effect

Answer 354

Compton Effect

Answer 355

Photoelectric Effect

Answer 356

Pair production

Answer 357

Annihilation

Answer 358

Wave nature

Answer 359

Particle nature

Answer 360

Both Wave nature and Particle nature

Answer 361

None of these

Answer 362

The scattered photon has frequency less than that of the incident photon

Answer 363

The scattered photon has frequency greater than that of the incident photon

Answer 364

The scattered photon has frequency equal to the incident photon

Answer 365

None of these

Answer 366

Pair production

Answer 367

Annihilation

Answer 368

X-rays Production

Answer 369

Compton Effect

Answer 370

Photoelectric Effect

Answer 371

Annihilation

Answer 372

X-rays Production

Answer 373

Compton Effect

Answer 374

The laws of physics are the same in all inertial frames of reference

Answer 375

The speed of light in free space is universal constant

Answer 376

The speed of light is independent of the speed of the observer

Answer 377

All of these

Answer 378

The Compton effect

Answer 379

ϒ-radiations

Answer 380

Photoelectric effect

Answer 381

Radiations pressure

Total Questions:	116
Time Allowed:	50 Minutes
Total Marks:	166
How to Attempt Test:	Please choose the right Option in MCQ-type question.
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