Test: Thermal Expansion - JEE MCQ

On heating, the copper strip will suffer greater elongation and hence the bimetal strip will bend with the steel strip on the concave side. 

[Bimetal strips are widely used in thermal switching applications such as automatic electric iron].

The rate of heat transfer is directly proportional to the bisectional surface area of the solid and inversely proportional to its parallel length. 
That is heat conduction rate say H ∝ r²
∝ 1/L
I.e ∝ r²/L
Hence the conduction would be
maximum in case in which  r²/L ratio is largest.

The Celsius and Fahrenheit are two important temperature scales. The Fahrenheit scale is used primarily in the United States, while Celsius is used throughout the world. The two scales have different zero points and the Celsius degree is bigger than the Fahrenheit one. There is one point on the Fahrenheit and Celsius scales where the temperatures in degrees are equal. This is -40 degree C and -40 degree F.

When heated the length between adjacent markings increases. Hence the actual length will be less than
30 cm.

Gas expands more than solid and liquid because gas particles are far apart hence freely move.

Cubical expansion means there is expansion is length (a1), breadth (a2) and height (a3). Therefore the net coefficient of cubical expansion is α1 + α2 + α3.

When water is heated from 0°C, its volume decreases because its density increases and you can see this effect upto 4°C. Since the density of ice is maximum at 4°C, afterwards as the density decreases the volume increases. The main reason for this is hydrogen bond in ice gets cleaved due to the melting of ice.

This is simple because the coefficients of linear expansion α_L, areal expansion α_A, and volume expansion α_v, are in the ratio of 1: 2: 3 i.e.:
α_L: α_A: α_v :: 1: 2: 3
Hence, α_v = 3α_L

When water is heated from 0^oC, its volume decreases because its density increases and you can see this effect upto 4^oC. Since the density of ice is maximum at 4^oC, afterwards as the density decreases the volume increases. The main reason for this is hydrogen bond in ice gets cleaved due to the melting of ice.