Physics · JEE | Dual Nature of Radiation and Matter

What is the minimum electric field strength required for field emission from a metal surface?

1. A
   \( 10^8 \text{ V m}^{-1} \)
2. B
   \( 10^6 \text{ V m}^{-1} \)
3. C
   \( 10^4 \text{ V m}^{-1} \)
4. D
   \( 10^{11} \text{ V m}^{-1} \)