MCQ
Q.
The heating element in an electric heater is made of which metal ?
Correct Answer: A
The correct answer is Nichrome.
Key Points
- Nichrome
- It is a metal alloy made up of around 20 percent of chromium and 80 percent nickel.
- The key to the workings of an electrical heating element is the role of the nichrome in it.
- Nichrome has fast emerged as the leading alloy to be used in terms of electrical heating elements.
- For an electric iron heater element should have higher resistance, high melting point, and high specific heat.
- An element should have high resistance so that it can hold its configuration in a high voltage current. It should have a high melting point such that it can sustain high temperatures.
- Nichrome is used as a heating element in electric iron which is an alloy consisting 80% of Nickel and 20% of Chromium melting point of this element is 1400 degrees Celsius with high resistance which makes this element best for use as a heating element. Hence, Option 1 is correct.
- The reason which makes the Nichrome best for heating elements is when it is heated in the air it develops an outer layer of chromium oxide which makes it stable in air and this chromium layer helps the element from oxidizing further during heating.
Additional Information
- Copper
- It is a chemical element with the symbol Cu and atomic number 29.
- It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity.
- A freshly exposed surface of pure copper has a pinkish-orange color.
- Silver
- It is a chemical element with the symbol Ag and atomic number 47.
- A soft, white, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal.
- Lead
- It is a chemical element with the symbol Pb and atomic number 82.
- It is a heavy metal that is denser than most common materials.
- Lead is soft and malleable, and also has a relatively low melting point.
- When freshly cut, lead is silvery with a hint of blue it tarnishes to a dull gray color when exposed to air.