A source S₁ is producing 10¹⁵ photons per sec of wavelength 5000 Å. Another source S₂ is producing 1.02×10¹⁵ photons per second of wavelength 5100 Å. Then, (power of S₂)/(power of S₁) is equal to:

1. 1.00

2. 1.02

3. 1.04

4. 0.98

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  \(3\times 10^{6}\) 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. \(2.7 \times 10^{-21}~\text{ms}^{-1}\)

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

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. $5\times {10}^{14}$