The potential difference that must be applied to stop the fastest photoelectrons emitted by a nickel surface, having work function 5.01 eV, when ultraviolet light of 200 nm falls on it, must be

1. 2.4 V

2. -1.2 V

3. -2.4 V

4. 1.2 V

 

A particle of mass 1 mg has the same wavelength as an electron moving with a velocity of 3 x 10⁶ ms^-1. The velocity of the particle is :
(Mass of electron = 9.1 x 10^-31 kg)

1.  $2.7\times {10}^{-18} {\mathrm{ms}}^{-1}$

2.  $9\times {10}^{-2} {\mathrm{ms}}^{-1}$

3.  $3\times {10}^{-31} {\mathrm{ms}}^{-1}$

4.  $2.7\times {10}^{-21} {\mathrm{ms}}^{-1}$

When photons of energy \(h\nu\) fall on an aluminium plate (of work function \(E_0\)), photoelectrons of maximum kinetic energy \(K\) are ejected. If the frequency of the radiation is doubled, the maximum kinetic energy of the ejected photoelectrons will be:
1. \(K+ E_0\)
2. \(2K\)
3. \(K\)
4. \(K + h\nu\)

The momentum of a photon of energy 1 MeV in kg m/s, will be :

1. $0.33\times {10}^6$

2. $7\times {10}^{-24}$

3. ${10}^{-22}$

4. $5\times {10}^{-22}$

An electron is accelerated through a potential difference of 10,000 V. Its de-Broglie wavelength is, (nearly) : ($m_e= 9\times {10}^{-31}kg$)

1. 12.2 nm

2. $12.2\times {10}^{-13}m$

3. $12.2\times {10}^{-12}m$

4. $12.2\times {10}^{-14}m$