The process of emission of electrons from hot metal surface is called
A. Field emission
B. Secondary emission
C. Thermionic emission
D. Photoelectric emission
Answer: Option C
Solution (By JKSSB Mock Tests)
Thermionic emission: electrons emitted when metal heated to high temperature (e.g., filament in cathode ray tube). Photoelectric: light incident. Field emission: strong electric field. Secondary: bombardment by particles.
Explanation:
Graphite, heavy water (D₂O), beryllium are moderators. Cadmium and boron are control rods (absorb neutrons). Uranium is fuel. Moderator slows neutrons.
Explanation:
In an open vessel, water boils at 100°C, and extra heat merely creates steam rather than raising the temperature. A pressure cooker traps steam, increasing the internal pressure above atmospheric pressure. Increased pressure raises the boiling point of water (often to around 120°C). Cooking the food at this higher temperature significantly reduces cooking time.
Explanation:
Fuse wire must melt easily (low melting point) to break circuit on overload, and have high resistance to produce sufficient heat (I²R). Materials: tin-lead alloy. Copper not used as fuse.
No comments yet. Be the first to start the discussion!