Question 4 :
If the temperature of the sun (black body) is doubled, the rate of energy received on earth will be increased by a factor of

Question 6 :
If the length of a cylinder on heating increases by 2%, the area of its base will increase by

Question 9 :
Four rods of silver, copper, brass and wood are of same shape. They are heated together after wrapping a paper on it, the paper will burn first on

Question 10 :
Total energy emitted by a perfectly black body is directly proportional to <img style='object-fit:contain' width=19 height=22 src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea132a427ce131ff7c05104"> where <img style='object-fit:contain' width=9 height=22 src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea132181ac76a0b860fa16e"> is

Question 11 :
Which of the following is more close to a black body?

Question 12 :
Three objects coloured black, gray and white can with stand hostile conditions at 2800 <img style='object-fit:contain' width=14 height=22 src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea131461ac76a0b860f9d6e"> . These objects are thrown into furnace where each of them attains a temperature of 2000 <img style='object-fit:contain' width=18 height=22 src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea1326c1ac76a0b860fa2c8"> Which object will glow brightest?

Question 13 :
The mechanical equivalent of heat <img style='object-fit:contain' width=6 height=20 src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea132901ac76a0b860fa378"> is

Question 14 :
If the ratio of coefficient of thermal conductivity of silver and copper is 10 : 9, then the ratio of the lengths upto which wax will melt in Ingen Hauz experiment will be

Question 15 :
A brass disc fits simply in a hole of a steel plate. The disc from the hole can be loosened if the system

Question 16 :
When the pressure on water is increased the boiling temperature of water as compared to <img style='object-fit:contain' width=38 height=20 src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea1314f1ac76a0b860f9dc1"> will be

Question 17 :
Mode of transmission of heat, in which heat is carried by the moving particles, is

Question 18 :
Which of the following is the correct device for the detection of thermal radiation

Question 20 :
The ratio of thermal conductivity of two rods of different material is 5:4. The two rods of same area of cross-section and same thermal resistance will have the lengths in the ratio

Question 21 :
A wire is loaded by $6 kg$ at its one end, the increase in length is $12 mm$. If the radius of the wire is doubled and all other magnitudes are unchanged, then increase in length will be<br><br>

Question 23 :
A solid cylindrical rod of radius $3 mm$ gets depressed under the influence of a load through $8 mm$. The depression produced in an identical hollow rod with outer and inner radii of $4 mm$ and $2 mm$ respectively, will be<br/>

Question 24 :
Two Metal strips are riveted together at their ends by four rivets, each of diameter {tex} \alpha = 6 \mathrm { mm } {/tex}. The maximum tension that can be exerted by the riveted strip (if the Shearing stress on the rivet is not to exceed {tex} 6.9 \times 10 ^ { 7 } \mathrm { Pa } {/tex} ) is?

Question 25 :
Maximum excess pressure inside a thin-walled steel tube of radius $r$ and thickness $\Delta r(&lt;&lt; r)$, so that tube would not rupture would be (breaking stress of steel is ${\sigma}_{max}$)<br>

Question 26 :
A cube is shifted to a depth of $100m$ is alake. The change in volume is $0.1$%. The bulk modules of the material is nearly<br>

Question 27 :
An area of cross-section of rubber string is $2cm^2$. Its length is doubled when stretched with a linear force of $2 \times 10^5 dynes$. The Young's modulus of the rubber in $dyne/cm^{2}$ will be<br><br>

Question 29 :
If Youngs modulus of iron is $2 \times 10^{11} N/m^{2}$ and the interatomic spacing between two molecules is $3 \times 10^{-10} metre$, the interatomic force constant is<br><br>

Question 30 :
A steel wire of length $L$ and area of cross-section A shrinks by $\Delta l$ during night. Find the tension developed at night if Young's modulus is $Y$ and wire is clamped at both ends<br/>

Question 31 :
A clock which keeps correct time at $20^{\circ}C$, is subjected to $40^{\circ}C$. If coefficient of linear expansion of the pendulum is $12\times 10^{-6}/ ^{\circ}C$, then how much will it gain or loss in time?

Question 32 :
Two rods, one of aluminum and the other made of steel, having initial length {tex} \ell _ { 1 } {/tex} and {tex} \ell _ { 2 } {/tex} are connected together to form a single rod of length {tex} \ell _ { 1 } + \ell _ { 2 } . {/tex} The coefficients of linear expansion for aluminum and steel are {tex} \alpha _ { a } {/tex} and {tex} \alpha _ { s } {/tex} and respectively. If the length of each rod increases by the same amount when their temperature are raised by {tex} t ^ { 0 } \mathrm { C } , {/tex} then find the ratio {tex} \ell _ { 1 } / \left( \ell _ { 1 } + \ell _ { 2 } \right) {/tex}

Question 33 :
A glass flask of volume one litre at $0^o$C is filled level full of mercury at this temperature. The flask and mercury are now heated to $100^o$C. How much mercury will spill out, if coefficient of volume expansion of mercury is $1.2\times 10^{-4}/^o$C and linear expansion of glass is $0.1\times 10^{-4}/^o$C, respectively?

Question 35 :
The ratio of the lengths of two rods is $4:3 $ . The ratio of their coefficients of cubical expasion is $ 2:3 $ . Then the ratio of their liner expansions when they are heated through same temperature difference is :

Question 36 :
Two wires are made of the same material and have the same volume. However first wire has crosssectional area {tex} A {/tex} and second wire has crosssectional area {tex} 3 A {/tex}. If the length of first wire increases by {tex} \Delta l {/tex} on applying force {tex} F, {/tex} how much force is needed to stretch second wire by the same amount?

Question 37 :
Take, bulk modulus of water $B = 2100\ MPa$.<br/>What increase in pressure is required to decrease the volume of $200\ litres$ of water by $0.004$ percent?

Question 38 :
Two wires are made of the same material and have the same volume. However wire {tex}1{/tex} has cross- sectional area {tex} A {/tex} and wire {tex}2{/tex} has cross-sectional area {tex} 9 A . {/tex} If the length of wire {tex}1{/tex} increases by {tex} \Delta x {/tex} on applying force {tex} F , {/tex} how much force is needed to stretch wire {tex}2{/tex} by the same amount?

Question 39 :
On observing light from three different stars {tex} \mathrm { P } , \mathrm { Q } {/tex} and {tex} \mathrm { R } {/tex} , it was found that intensity of violet colour is maximum in the spectrum of {tex} \mathrm { P } {/tex} , the intensity of green colour is maximum in the spectrum of {tex} \mathrm { R } {/tex} and the intensity of red colour is maximum in the spectrum of {tex} \mathrm { Q } {/tex}. If {tex} \mathrm T_{ \mathrm P},\, \mathrm T _ { \mathrm Q } {/tex} and {tex} \mathrm T _ { \mathrm R } {/tex} are the respective absolute temperature of {tex} \mathrm{P , Q} {/tex} and {tex} \mathrm R , {/tex} then it can be concluded from the above observations that

Question 40 :
In performing an experiment to determine the Young's modulus Y of steel, a student can record the following values:<br>length of wire l$=(\ell_{0}\pm\Delta$l$){m}$<br>diameter of wire ${d}=({d}_{0}\pm\Delta {d})$ mm<br>force applied to wire ${F}$=$({F}_{0}\pm\Delta {F}){N}$<br>extension of wire ${e}=({e}_{0}\neq\Delta {e})$ mm<br>In order to obtain more reliable value for Y, the followlng three techniques are suggested. <br>Technique (i) A shorter wire ls to be used.<br>Technique (ii) The diameter shall be measured at several places with a micrometer screw gauge.<br>Technique (iii) Two wires are made irom the same ntaterial and of same length. One is loaded at a fixed weight and acts as a reference for the extension of the other which is load- tested<br>Which of the above techniques is/are useful?<br>

Question 41 :
A piece of ice falls from a height h so that it melts completely. Only one-quarter of the heat produced is absorbed by the ice and all energy of ice gets converted into heat during its fall. The value of h is: {tex} \left. \text { [Latent heat of ice is } 3.4 \times 10 ^ { 5 } \mathrm { J } / \mathrm { kg } = 10 \mathrm { N } / \mathrm { kg } \right] {/tex}<br>

Question 42 :
A uniformly tapering conical wire is made from a material of Young's modulus {tex}\mathrm Y{/tex} and has a normal, unextended length {tex}\mathrm L{/tex} . The radii, at the upper and lower ends of this conical wire, have values {tex}\mathrm R{/tex} and {tex} 3 \mathrm { R } , {/tex} respectively. The upper end of the wire is fixed to a rigid support and a mass {tex} \mathrm { M } {/tex} is suspended from its lower end. The equilibrium extended length, of this wire, would equal: {tex} \quad {/tex}

Question 43 :
A metallic rod {tex} \ell \mathrm { cm } {/tex} long, {tex} \mathrm { A } {/tex} square {tex} \mathrm { cm } {/tex} in cross-section is heated through {tex} \mathrm { t } ^ { \circ } \mathrm { C } {/tex} . If Young's modulus of elasticity of the metal is {tex} \mathrm { E } {/tex} and the mean coefficient of linear expansion is {tex} \alpha {/tex} per degree celsius, then the compressional force required to prevent the rod from expanding along its length is<br>

Question 44 :
A plattorm is suspended by four wires at its corners. The wires are {tex} 3 \mathrm { m } {/tex} long and have a diameter of {tex} 2.0 \mathrm { mm } {/tex}. Young's modulus for the material of the wires is {tex} 1,80,000 \mathrm { MPa } {/tex}. How far will the platform drop (due to elongation of the wires) if a {tex} 50 \mathrm { kg } {/tex} load is placed at the centre of the platform?<br>

Question 45 :
When the temperature of a rod increases from {tex}\mathrm t{/tex} to {tex} \mathrm { t } + \Delta \mathrm { t } {/tex} , its moment of inertia increases from {tex}\mathrm I{/tex} to {tex} \mathrm { I } + \Delta \mathrm { I } {/tex} . If {tex} \alpha {/tex} be the coefficient of linear expansion of the rod, then the value of {tex} \frac { \Delta \mathrm { I } } { \mathrm { I } } {/tex} is<br>