Dual Nature of Matter

Assertion : Work function of aluminium is $4.2 \mathrm{eV}$. Emission of electrons will not be possible if two photons, each of energy $2.5 \mathrm{eV}$, strike an electron of aluminium. Reason : For photoelectric…

Assertion : A photon has no rest mass, yet it carries definite momentum. Reason : Momentum of photon is due to its energy and hence its equivalent mass.

The energy flux of sunlight reaching the surface of the earth is $1.388 \times 10^3 \mathrm{~W} \mathrm{~m}^{-2}$. How many photons (nearly) per square metre are incident on the earth per second? Assume that the photons…

Assertion: The relative velocity of two photons travelling in opposite direction is the velocity of light. Reason : The rest mass of photon is zero.

The potential difference $V$ required for accelerating an electron to have the de Broglie wavelength of $1 Å$ is

The maximum velocities of the photoelectrons ejected are $v$ and $2 v$ for the incident light of wavelength $400 \mathrm{~nm}$ and $250 \mathrm{~nm}$ on a metal surface respectively. The work function of the metal in…

Assertion : The de Broglie wavelength of a molecule varies inversely as the square root of temperature. Reason : The root mean square velocity of the molecule depends on the temperature.

Maximum velocity of the photoelectron emitted by a metal is $1.8 \times 10^6 \mathrm{~m} \mathrm{~s}^{-1}$. Take the value of specific charge of the electron is $1.8 \times 10^{11} \mathrm{C} \mathrm{kg}^{-1}$. Then the…

An electron moving with speed $v_1$ has wavelength $\lambda_1$ and another electron moving with speed $v_2$ has wavelength $\lambda_2$, find $\left(v_1^2-v_2^2\right)$. ($m_e=$ mass of electron)

A deutron has an energy of $4 \mathrm{MeV}$ when accelerated through a potential difference $V$. What will be the energy of an $\alpha$-particle accelerated by source $V$ ?

Assertion : Photoelectric effect demonstrates the wave nature of light. Reason: The number of photoelectrons is proportional to the frequency of light.

If the maximum kinetic energy of emitted photo electrons from a metal surface of work function $2.5 \mathrm{eV}$, is $1.7 \mathrm{eV}$. If wavelength of incident radiation is halved, then stopping potential will be