Question

A red hot iron ball is suspended from the ceiling of a room by a thin metallic wire.
A) The ball losses heat in the form of conduction and convention only.
B) The loss of head is least by conduction method.
C) A convection current is set in the air.
Which of the following statements is true?
A. Only B
B. Both A and B
C. Both B and C
D. All are correct

Answer 1

Hint: A heated body loses heat in three ways depending upon the conditions met. When two conductors are met, heat loss occurs through conduction. Heat Loss through Convection occurs when the hot body is placed in a cooler fluid. And through radiation, if the body is significantly hotter than its surrounding.

Complete answer:
Heat loss is the loss of thermal energy as heat to the surrounding. A hotter loses its heat to a colder body or surrounding.
There are 3 ways of heat loss: -
1) Conduction
Heat conduction, or diffusion, happens when two bodies are in direct contact. It also happened within the body itself. It is the direct exchange of kinetic energy between the particles of touching bodies. Heat transfers occur till both the bodies in contact acquire the same temperature.
2)Convection
This happens when the hotter body is kept under the bulk of the cooler fluid. Here the fluid particles move and take heart from the hotter body as they move along.
3) Radiation
Here the heat is lost through electromagnetic radiation. Heat loss through radiation occurs when a surface is considerably hotter than its surrounding.
Coming to the question
A red-hot iron ball is suspended from the ceiling of a room by a thin metallic wire. The iron ball will lose heat through all three methods. So A is not true.
Since the metal wire connected to the red hot is thin thus the heat loss will be very small. So B is true
And since the iron ball is significantly hot it will start a convection current in the surrounding air. So C is true.
Statements B and C are true

Therefore, Option C is correct.

Note:
A convection current is due to the temperature (or density) differences within the fluid. In these currents, there is a movement of particles from one place to another. Many natural phenomena take place due to convection currents. For instance, boiling of water or changes in weather are all a result of convection currents.