Question
Why does the cord of an electric heater not glow while the heating element does ?
✓
Answer
→ Cord of an electric heater is made of copper wire which has low resistivity and low resistance. Hence for given current passing through it for given time, amount of heat produced in it is also small according to $H=I^2 R t$. Hence it does not glow as it does not become hot.
→ An electric heater is made up of coil of alloy like Nichrome which has high resistivity and high resistance. Hence for given current passing through it for given time, amount of heat produced in it is also large according to $H=I^2 R t$. Hence it becomes red hot because of quick rise in temperature due to Joule's heating. That is why heating element start glowing.
→ An electric heater is made up of coil of alloy like Nichrome which has high resistivity and high resistance. Hence for given current passing through it for given time, amount of heat produced in it is also large according to $H=I^2 R t$. Hence it becomes red hot because of quick rise in temperature due to Joule's heating. That is why heating element start glowing.
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
What is vegetative propagation? State the advantages of it.
What is called displacement reaction ? Explain with example.
State the basic features of inheritance of traits.
A convex mirror used for rear$-$view on an automobile has a radius of curvature of $3.00 m$. If a bus is located at $5.00 m$ from this mirror, find the position, nature and size of the image.
→→
What is meant by combustion? Explain it by giving an example.
Give scientific reason:
The property of vegetative propagation is useful in agricultural purposes.
The property of vegetative propagation is useful in agricultural purposes.
Explain the following in terms of gain or loss of oxygen with two examples each.
$(a)$ Oxidation
$(b)$ Reduction
→$(a)$ Oxidation
$(b)$ Reduction
Write a short note on compass.
Ashish noticed that his friend always brought sweets in his lunch-box, due to which his tooth decayed. Ashish suggested his friend to eat less sweets in school hours to avoid tooth decay.
(1) Why do tooth decay on eating sweets?
(2) What is the pH of mouth after eating sweets?
(3) What value of Ashish is seen in the above act?
(1) Why do tooth decay on eating sweets?
(2) What is the pH of mouth after eating sweets?
(3) What value of Ashish is seen in the above act?