On increasing the temperature of a substance gradually, which of the following colours will be noticed by you
A
White
B
Yellow
C
Green
D
Red
Easy
Download our app for free and get started
A
White
a (a) White. The temperature of body is at $1600^{\circ} \mathrm{C}$
Temp
Colour
Temp.
Colour
$525\circ C$
Light red
$1200\circ C$
Yellow
$900\circ C$
Cherry red
$1300\circ C$
Green
$1100\circ C$
Orange red
$1600\circ C$
White
According to Wien's displacement law, $\lambda T=$ constant. For red, $\lambda$ is large sotemperature is less. For blue temperature is large accordingly.
Download our app
and get started for free
Experience the future of education. Simply download our apps or reach out to us for more information. Let's shape the future of learning together!No signup needed.*
Three identical rods have been joined at a junction to make it a $Y$ shape structure. If two free ends are maintained at $90\,^oC$ and the third end is at $30\,^oC$ , then what is the junction temperature $\theta $ ?......... $^oC$
Two spherical bodies $\mathrm{A}$ (radius $6 \mathrm{~cm}$ ) and $\mathrm{B}$ (radius $18 \mathrm{~cm}$ ) are at temperature $\mathrm{T}_1$ and $\mathrm{T}_2$, respectively. The maximum intensity in the emission spectrum of $\mathrm{A}$ is at $500 \mathrm{~nm}$ and in that of $\mathrm{B}$ is at $1500 \mathrm{~nm}$. Considering them to be black bodies, what will be the ratio of the rate of total energy radiated by $A$ to that of $B$ ?
If between wavelength $\lambda $and $\lambda + d\lambda $, ${e_\lambda }$and ${a_\lambda }$ be the emissive and absorptive powers of a body and ${E_\lambda }$ be the emissive power of a perfectly black body, then according to Kirchoff's law, which is true
On observing light from three different stars $P, Q$ and $R$, it was found that intensity of violet colour is maximum in the spectrum of $P$, the intensity of green colour is maximum in the spectrum of $R$ and the intensity of red colour is maximum in the spectrum of $Q$. If $T_P, T_Q$ and $T_R$ are the respective absolute temperatures of $P, Q$ and $R$, then it can be concluded from the above observations that
$A$ wall is made up of two layers $A$ and $B$ . The thickness of the two layers is the same, but materials are different. The thermal conductivity of $A$ is double than that of $B$ . In thermal equilibrium the temperature difference between the two ends is ${36^o}C$. Then the difference of temperature at the two surfaces of $A$ will be ....... $^oC$
A spherical black body with a radius of $24\;cm$ radiates $440\;W$ power at $500\;K$. If the radius were halved and the temperature doubled, the power radiated in watt would be