English
Karnataka Board PUCPUC Science Class 11

Standing in the Sun is More Pleasant on a Cold Winter Day than Standing in Shade. is the Temperature of Air in the Sun Considerably Higher

Advertisements
Advertisements

Question

Standing in the sun is more pleasant on a cold winter day than standing in shade. Is the temperature of air in the sun considerably higher than that of the air in shade?

Short/Brief Note
Advertisements

Solution

The heat coming from the sun to us is through the radiation. On colder winter days, when we stand in shade, we do not get the heat of the sun from the radiation. Though we feel cool in the shade, the temperature of the air in shady as well as non-shady regions is the same.

shaalaa.com
  Is there an error in this question or solution?
Chapter 28: Heat Transfer - Short Answers [Page 97]

APPEARS IN

HC Verma Concepts of Physics Volume 1 and 2 [English]
Chapter 28 Heat Transfer
Short Answers | Q 9 | Page 97

RELATED QUESTIONS

Explain why an optical pyrometer (for measuring high temperatures) calibrated for an ideal black body radiation gives too low a value for the temperature of a red hot iron piece in the open but gives a correct value for the temperature when the same piece is in the furnace


Explain why the earth without its atmosphere would be inhospitably cold


Why does blowing over a spoonful of hot tea cools it? Does evaporation play a role? Does radiation play a role?


Two identical metal balls one at T1 = 300 K and the other at T2 = 600 K are kept at a distance of 1 m in a vacuum. Will the temperatures equalise by radiation? Will the rate of heat gained by the colder sphere be proportional to `t_2^4 - t_1^4` as may be expected from the Stefan's law?


Cloudy nights are warmer than the nights with clean sky. Explain


Assume that the total surface area of a human body is 1.6 m2 and that it radiates like an ideal radiator. Calculate the amount of energy radiated per second by the body if the body temperature is 37°C. Stefan constant σ is 6.0 × 10−8 W m−2 K−4.


A solid aluminium sphere and a solid copper sphere of twice the radius are heated to the same temperature and are allowed to cool under identically surrounding temperatures. Assume that the emissivity of both the spheres in the same. Find the ratio of (a) the rate of heat loss from the aluminium sphere to the rate of heat loss from the copper sphere and (b) the rate of fall of temperature of the aluminium sphere to the rate of fall of temperature of the copper sphere. The specific heat capacity of aluminium = 900 J kg−1°C−1 and that of copper = 390 J kg−1°C−1. The density of copper = 3.4 times the density of aluminium.


A spherical ball A of surface area 20 cm2 is kept at the centre of a hollow spherical shell B of area 80 cm2. The surface of A and the inner surface of B emit as blackbodies. Both A and B are at 300 K. (a) How much is the radiation energy emitted per second by the ball A? (b) How much is the radiation energy emitted per second by the inner surface of B? (c) How much of the energy emitted by the inner surface of B falls back on this surface itself?


A cylindrical rod of length 50 cm and cross sectional area 1 cm2 is fitted between a large ice chamber at 0°C and an evacuated chamber maintained at 27°C as shown in the figure. Only small portions of the rod are inside the chamber and the rest is thermally insulated from the surrounding. The cross section going into the evacuated chamber is blackened so that it completely absorbs any radiation falling on it. The temperature of the blackened end is 17°C when steady state is reached. Stefan constant σ = 6 × 10−8 W m−2 K−4. Find the thermal conductivity of the material of the rod.


Wein's constant is 2892 × 10-6 SI unit and the value of λm for moon is 14.46 micron. The surface temperature of moon is ______.


A student says, "Heat from the Sun reaches Earth because air carries it across space." Which statement best explains why this is incorrect?


You place your hands near a burning candle and feel warmth on both sides of the flame. What does this observation mainly show?


Which statement best describes thermal radiation from everyday objects like trees, roads, and buildings at night?


Why are cooking utensils like pans made of metal but fitted with plastic or wooden handles?


According to Stefan–Boltzmann Law, if the temperature of a body is doubled (in Kelvin), the heat emitted by it becomes ______.


A perfect black body has an emissivity value of ______.


In the experiment where a test tube of water is heated from the top with ice at the bottom, the ice does not melt. What is the primary reason for this?


Which of the following properties is shared by both thermal radiation and visible light?


Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Use app×