12th Class PHYSICS MCQs CHAPTER NO.8 DAWN OF MODERN PHYSICS Test No.1

In an expression for time dilation, the quantity √1-v²/c²is always

Absolute motion of a body

A particle and its antiparticle, together at one place

An expression for Compton shift &inc;&lambda for angle θ is given as

An human eye can detect the electormegnetic radiations of the type

When a platinum wire is heated, at 1600^°ree;C it becomes

A non-inertial frame of reference is that which

If speed of light were infinity, then moving mass m becomes

he photoelectric effect was explained by

In photoelectric effect, if intensity of incident radiation is increased, then there is increase in

The minimum energy required by a photon to create a electron-positron pair is

The rest mass energy of an electron is

The photoelectric effect can be explained on the basis of

A coordinate system relative to which measurement are taken is known as

If an object moves with a velocity of light, then the apparent length of the object along the direction of motion becomes

If a material object moves with speed of light, its mass becomes

The nature of radiation emitted by a body depends upon

The momentum of a photon is

The special theory of relativity is applicable to the objects moving with

In Compton effect, the wavelength of the scattered photon as compard to the wavelength of incident X-rays is

According to Max Plank, energy is released or absorbed in discrete packets called

A.H. Compton studied the X-rays by loosely bound electrons from a graphite target in

The name of photon for a quantum of light energy was first introduced by

Modern physics mainly based upon

The numerical value of Compton wavelength h/m_°ree;c is equal to

The phenomenon which proves Einstein's relation (E = mc²) is

Assuming you radiate as does a black body at a temperature about 17^°ree;C, the wavelength of the emitted radiation is

Compton effect makes use of law of conservation of

The maximum energy of the photoelectrons can be determined by making the

If the speed of light becomes infinite, then the mass of electron moving with velocity 3 x 10⁸ m/s becomes [m₀ it the rest mass of electron]

The length contraction happens only

Max Plank suggested that energy is released or absorbed in discrete packets in

Special theory of relativity was given in

The energy of a photon is given by

In a photocell, sodium and potassium emit electrons for

Black body energy distribution curves are the graphs between

The number of photoelectrons emitted (or photoelectric current) is directly proportional to the

In a photcell, cesium coated oxidized silver emits electrons for

There is a certain frequency below which no electrons are emitted from the metal surface, this frequency is known as:

The maximum energy of the photoelectrons is given by the equation

At high temperature, the proprtion of shorter wavelength radiation

Radiations are always emitted or absorbed in the form of packets of energy. This is the statement of

The pair production equation can be written as

0.1 kg mass will be equivalent to the energy

For Pair production minimum energy of photon must be

If we are strictly speaking, then earth is

The part of theory of relativity which deals with inertial or non-accelerating frames of reference is known as

When the temprature of the body is increased, the radiation becomes richer in

The momentum of a photon frequency f is

When a very high energy photon interact with a matter, then the following phenomenon taken place

The value of Plank's constant h is given by

The pair production and annihilation of matter are

In Compton shift, the factor h/m_°ree;c is known as

The discrete nature of radiation was introduced by

The mass of an object will be doulbed at speed

Which photon, red, green, or blue carries the most energy?

The maximum kinetic energy of emitted photoelectrons depends upon

The value of Stefen's constant is

Black bodies are formed of

An intertial frame of reference is that for which

When a platinum wire is heated, it appears cherry red at about

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

When a platinum wire is heated, it appears white at about

The anti matter theory was proposed by

The velocity at which the relativistic length of a body reduces to half of its original length is

A positron is a antiparticle of

Energy of asingle quanta of elctromagnetic radiation is given the name

For an electron or positron, the rest-mass energy is equal to

A frame of reference which remains at rest or moves with uniform velocity is called

According to special theory of relativity, time is

The relativistic change in mass, length and time in daily life are not observed because

The theory of relativity was proposed by

All motions are

In annihilation of matter, positron and electron pair disappears into two

A device based on photoelectric effect is called

Photoelectric effect was discovered by

Photo electric effect is the converse process of

A particle with rest mass 'm_°ree;' and relativistic mass 'm' has kinetic energy equal to

A photon is considered to have

In a photocell, certainmetals emit electrons for

According to special theory of relativity, all laws of physics are same in all

The mass m of a body moving at 0.8 C becomes

The branch of physics which deals with the behaviour of microscopic particles moving with speed of light is called

The Einstein-energy mass relation can be expressed as

Which of the following radiations has photons of maximum energy

Due to the relative motion of observer and frame of reference, time

At what angle, the Compton shift '&inc;λ' equals the Compton wavelength?

Wien's theory explains energy distributon in black body for

The special theory of relativity is based

The speed of light in free space is

Pair production can take place by using

A frameof reference in which law of inertia is valid is known as

A beam of red light and a beam of blue light have exactly the same energy. Which beam contains the greater number of photons?

The classical physics is based upon the laws of

In photoelectric effect, light exhibits

In the process of annihilation of matter, the two photons produced move in opposite directino to conserve

In photoelectric effect, emitted electrons are called

A high temperature, a body generally emits radiations of

The theory of relativity which deals with non-inertial frame of reference is called

Einstein got the Nobel Prize in physics for his explanation of photoelectric effect in

Phenomena such as black body radiation , photoelectric effect, the emission of sharp spectral lines by atoms in a gas discharge tube were explained by

The process of pair production takes place if the energy of photon is at least

When a platinum wire is heated, it appears orange at about

The process in which energy is converted into meter is called

The rest mass of a photon is

The length of an object or distance between two points measured by an observer who is relatively at rest is called

The earth's orbital speed is only

Positron was discovered by Carl Anderson in

In the wien's displacement law i.e. λ_m x T = constant, the value of constant is

If the temperature of a black body is doubled, the total radiation from the body becomes

The stopping potential (V_°ree;) in photoelectric effect depends on the

The dimensions of Plank's constant h are same as that of

The speed of photon as compared with the speed of light is always

Photocell is a device which converts

Einstein s photo electric equation is given by

When the K.E._max of photoelectron is zero, the frequency of incident photon is______that of threshold frequency

The photoelectric effect can be explained by

A black body is that which aborbs

The emission of electorns from a metal surface when exposed to light of suitable frequency is called

In Compton effect, it was considered that X-rays consist of

Absorption power of perfect black body is

Pair production confirms the