Thermal Expension, Thermometry

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What is the primary reason for thermal expansion in solids?

Increase in amplitude of vibration of atoms with temperature (correct)

Decrease in potential energy of atoms with temperature

Increase in intermolecular force with temperature

Decrease in average distance between atoms with temperature

What type of thermal expansion is exhibited by liquids and gases?

Superficial expansion

Linear expansion

Two-dimensional expansion

Volume expansion (correct)

What is the unit of the coefficient of linear expansion?

m°C

m/°C

°C

/°C (correct)

What is the reason for minimum thermal expansion in solids?

Maximum intermolecular force Signup and view all the answers

What is the relationship between the coefficients of linear, superficial, and volume expansions?

α = β = γ Signup and view all the answers

What is the coefficient of volume expansion of a substance?

The change in volume per unit original volume per unit change in temperature Signup and view all the answers

What is the relationship between the coefficients of linear expansion and volume expansion for anisotropic solids?

γ = αx + αy + αz Signup and view all the answers

What is the unit of coefficient of linear expansion?

K^-1 or (°C)^-1 Signup and view all the answers

What happens to the density of a substance when it is heated?

It decreases Signup and view all the answers

What is the purpose of designing a physical instrument with a constant difference in length of 10 cm between an iron rod and a copper cylinder?

To ensure that the instrument remains stable at all temperatures Signup and view all the answers

What is the reason behind leaving space between the ends of two rails when laid down on the ground?

To allow for expansion during summer Signup and view all the answers

Why are test tubes, beakers and crucibles often made of pyrex-glass or silica?

Because they have low coefficient of linear expansion Signup and view all the answers

What is the reason behind using invar alloy for making pendulum of wall clock and balance wheel of wrist watch?

Because it has a low coefficient of expansion Signup and view all the answers

What is the effect of thermal expansion on the hollow sphere?

The expansion of the hollow sphere is equal to that of a solid sphere of the same radius and material Signup and view all the answers

Why is the iron rim to be put on a cart wheel made of slightly smaller diameter than that of the wheel?

To allow for thermal expansion Signup and view all the answers

What is the relationship between the specific heat of a solid and the slope of its temperature-time curve?

It is inversely proportional to the slope of the temperature-time curve. Signup and view all the answers

In the region where the temperature of a substance is constant, what is happening to the substance?

The substance is undergoing a change of state. Signup and view all the answers

For anisotropic solids, the coefficient of volume expansion γ is equal to:

αx + αy + αz Signup and view all the answers

What is the relationship between the latent heat of fusion and the length of the line of zero slope on a temperature-time curve?

The latent heat of fusion is directly proportional to the length of the line of zero slope. Signup and view all the answers

A thermometer is designed to have a constant difference in length of 10 cm between an iron rod and a copper cylinder laid side by side at all temperatures. If αFe = 11 × 10^-6°C^-1 and αCu = 17 × 10^-6°C^-1, what are the lengths of the iron rod and copper cylinder?

23.8 cm, 13.8 cm Signup and view all the answers

The density of a substance decreases with an increase in temperature due to:

increase in volume Signup and view all the answers

What is the specific heat of a substance in the region where its temperature is changing?

It is inversely proportional to the slope of the temperature-time curve. Signup and view all the answers

The binomial theorem is used to simplify the expression for the density of a substance at a given temperature, which is:

ρ = ρ(1 - γΔT) Signup and view all the answers

What is the state of a substance in the region where its temperature is constant and its specific heat is infinite?

It is partly solid and partly liquid. Signup and view all the answers

Isotropic solids have a coefficient of volume expansion that is:

three times the coefficient of linear expansion Signup and view all the answers

What is the main reason behind the independence of the expansion of a body's area or volume from the shape and size of the hole or cavity?

The thermal expansion of isotropic solids is similar to true photographic enlargement Signup and view all the answers

Why is the rise in temperature of a hollow sphere more than that of a solid sphere of the same material when heated to the same temperature?

Due to the lesser mass of the hollow sphere Signup and view all the answers

What is the primary reason behind the use of pyrex-glass or silica for making test tubes, beakers, and crucibles?

They have a low coefficient of linear expansion Signup and view all the answers

Why are transmission cables not tightly fixed to the poles?

To prevent the cable from being damaged due to thermal expansion Signup and view all the answers

What is the main advantage of using invar alloy for making pendulum of wall clock and balance wheel of wrist watch?

It has a low coefficient of linear expansion Signup and view all the answers