An electron is accelerated through a potential difference of \(10,000~\text{V}\). Its de-Broglie wavelength is, (nearly):
\(\left(m_e = 9\times 10^{-31}~\text{kg}\right )\)
1. \(12.2~\text{nm}\)
2. \(12.2\times 10^{-13}~\text{m}\)
3. \(12.2\times 10^{-12}~\text{m}\)
4. \(12.2\times 10^{-14}~\text{m}\)

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. $5\times {10}^{-22}$

When photons of energy h$\nu$ fall on an aluminium plate (of work function E₀), 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$\nu$

A photocell employs a photo-electric effect to convert:

Monochromatic light of frequency 6.0×10¹⁴ Hz is produced by a laser. The power emitted is 2×10^-3 W. The number of photons emitted, on average, by the source per second is:

1. $5\times {10}^{15}$

2. $5\times {10}^{16}$

3. $5\times {10}^{17}$

4. $5\times {10}^{14}$

A \(5~\text W\) emits monochromatic light of wavelength \(5000~\mathring{A}.\) When placed \(0.5~\text m\) away, it liberates photoelectrons from a photosensitive metallic surface. When the source is moved \(1.0~\text m\) away, the number of photoelectrons liberated is reduced by a factor of:
1. \(4\)
2. \(8\)
3. \(16\)
4. \(2\)

A particle of mass \(1\) mg has the same wavelength as an electron moving with a velocity of  \(3\times 10^{6}\) ms^-1. The velocity of the particle is:
(Mass of electron = \(9.1 \times 10^{-31}\) kg)
1. \(2.7 \times 10^{-18}~\text{ms}^{-1}\)
2. \(9 \times 10^{-2}~\text{ms}^{-1}\)
3. \(3 \times 10^{-31}~\text{ms}^{-1}\)
4. \(2.7 \times 10^{-21}~\text{ms}^{-1}\)