A. VERY SHORT ANSWER TYPE QUESTIONS
1. Which metal is used to make heating element ?
2. What is electric current ?
3. When does a bulb glow in a circuit ?
4. What is used to generate electricity in CFLs ?
5. On which principle does an electric bell function ?
6. Which effect of electric current is utilised in the working of an electric fuse?
Answers
Answer:
1)Nichrome
Nichrome: Most resistance wire heating elements use nichrome 80/20 (80% Nickel, 20% Chromium) wire, ribbon, or strip. Nichrome 80/20 is an ideal material, because it has relatively high resistance and forms an adherent layer of chromium oxide when it is heated for the first time.
2) An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is measured as the net rate of flow of electric charge past a region.
3) An electric bulb glows when electric current passes through it. In a closed electric circuit, the electric current passes from one terminal of the electric cell to the other terminal.
4) In a CFL, an electric current is driven through a tube containing argon and a small amount of mercury vapor. This generates invisible ultraviolet light that excites a fluorescent coating (called phosphor) on the inside of the tube, which then emits visible light.
5) When an electric current flows through the coils, the electromagnet creates a magnetic field which pulls the armature towards it, causing the hammer to strike the bell.
6) Heating effect
Heating effect of current is used in the working of electric fuse.