Heat and Temperature Measurement

A clinical thermometer is used to measure the body temperature which normally remains between $35^{\circ}$C and $42^{\circ}$C.

People boil water as safe measure to drink because excessive heating kills the microorganisms present in the water and becomes safe to drink it.

Alcohol has a low freezing point.

Mercury is the only one in liquid state at room temperature. It's used in thermometers because it has high coefficient of expansion. Hence, the slightest change in temperature is notable when it's used in a thermometer. It also has a high boiling point which makes it very suitable to measure higher temperatures, and it doesn't stick to glass.

The lower fixed point, or ice point, is the temperature of pure melting ice at normal atmospheric pressure. The upper fixed point, or steam point, is the temperature of pure boiling water at normal atmospheric pressure.

If the correct heading of barometer at $0^oC$ is $70\ cm$ then the at $40^oC,$ the reading will show,

Using the linear relationship for a constant volume gas thermometer, T = ((P - P0) / (P100 - P0)) * 100. Substituting values: ((32.45 - 27.50) / (37.50 - 27.50)) * 100 = (4.95 / 10) * 100 = 49.5 C.

The brass scale expands at 15°C, making divisions larger. Apparent reading is smaller. Brass scale factor = 1 + 20×10^-6 × 15 = 1.0003. True height = 74.9 × 1.0003 = 74.8778 cm. Correcting for mercury contraction from 15°C to 0°C: final height = 74.8778 / (1 + 175×10^-6 × 15) = 74.8778 / 1.0026 = 74.72 cm.

Mercury thermometer is based on the principle of change of volume with rise of temperature and can measure temperatures ranging from $-{30}^{\circ}$C to ${357}^{\circ}$C.

Mercury, which is used as a thermometric liquid, has the following characteristic properties:

1. Mercury has a high boiling point of about $357^{\circ}$C and therefore can be used to measure temperatures as high as $357^{\circ}$C.

2. Mercury has a freezing point of about $-39^{\circ}$C and hence it is suitable in thermometers to record low temperatures (although not very low temperatures).

3. Mercury is opaque and has a shining silvery colour of its own, making it clearly visible in the capillary tube of a thermometer. 

A thermometer is a device that measures temperature or a temperature gradient. A thermometer has two important elements: (1) a temperature sensor (e.g. the bulb of a mercury-in-glass thermometer or the digital sensor in an infrared thermometer) in which some change occurs with a change in temperature, and (2) some means of converting this change into a numerical value (e.g. the visible scale that is marked on a mercury-in-glass thermometer or the digital readout on an infrared model). Thermometers are widely used in industry to monitor processes, in meteorology, in medicine, and in scientific research

The above statement is false.

A thermometer is a tool that measures temperature — how hot or cold something is.Made up of thermo (heat) and meter (measuring device), the meaning of the word thermometer is pretty straightforward. Thermometers measure temperatures in degrees, according to either the Celsius or Fahrenheit system.

A bolometer is a device used for measuring the power of incident electromagnetic radiation via the heating of a material with a temperature-dependent electrical resistance.

A gas thermometer measures temperature by the variation in volume or pressure of a gas.This thermometer functions by Charles's Law. Charles's Law states that when the temperature of a gas increases, so does the volume.

Mercury is commonly used in thermometers because it has a high coefficient of thermal expansion, remains liquid over a wide temperature range, and provides a clear, visible reading.

The overflow volume is given by V * deltaT * (gamma_liquid - gamma_glass). Assuming the weight thermometer expansion is negligible or included in the effective coefficient, the overflow mass is m * deltaT * gamma_alcohol. 45 * (33-15) * 121 * 10^-5 = 45 * 18 * 0.00121 = 0.9801 gm, which rounds to 1 gm.

Increase in length of each liquid is same 

Option (A) is correct. 

Heat given by water $=100\times 1\times 800=8000 cal$
Heat taken by ice $=8000 cal=m\times 80$
$m=100 gm$
So amount of ice which does not melt $=150-100=50 gm$.

All three will be inthermal equilibrium with air of room. so temprature of the three will be same

$t _x = 3 T + 300                 Q = ms \Delta 0$
$\Delta t _x = 3 \Delta T$
$\displaystyle S = \frac{Q}{m \Delta \theta}                 S = \frac{Q}{m \Delta \theta}$
Since, unit of 8 is joule in both system
            X                                    T
$m = m _0 kg$                   $m _0 kg$
$Q = Q _0 J$                       $Q _0  J$
$\Delta t _x$                               $\Delta T$
$S _x = \displaystyle \frac{Q _0}{m _0 \Delta t _x} = 1400     S _r = \frac{Q _0}{m _0 \Delta T} = \frac{3 Q}{m _0 \Delta t _x}$
$S _r = 3 \times 1400 = 4200 J-kg^{-1} K^{-1}$

The correct answer is option(C).

Iron glows in red colour when it is heated to very high temperature cause heat energy is being converted into light energy.

The correct answer is option(B).

heat is a type of energy transfer in which energy flows from a warmer substance or object to a colder one. It can be defined as the total amount of transferred energy excluding any macroscopic work that was done and any transfer of part of the object itself. Transfer of energy as heat can occur through direct contact, through a barrier that is impermeable to matter (as in conduction), by radiation between separated bodies, by way of an intermediate fluid (as in convective circulation), or by a combination of these. By contrast to work, heat involves the stochastic (random) motion of particles (such as atoms or molecules) that is equally distributed among all degrees of freedom, while work is confined to one or more specific degrees of freedom such as those of the center of mass.

 wooden spoon is dipped in a cup of ice cream. It's another end does not become cold as wood is a bad conductor of heat

Thermal Equilibrium - A system is said to be in thermal equilibrium when there is no temperature difference between system and surroundings.

Heat can be transferred from one place to another by three methods: conduction in solids, convection of fluids (liquids or gases), and radiation through anything that will allow radiation to pass. The method used to transfer heat is usually the one that is the most efficient. If there is a temperature difference in a system, heat will always move from higher to lower temperatures.

Absolute temperature in Celsius is $-273.15{{\,}^{o}}C$

$ F=\dfrac{9}{5}C+32 $

$ F=\dfrac{9}{5}\times (-273.15)+32=-459.67{{\,}^{o}}F $

$ F\cong -460{{\,}^{o}}F $

Hence, absolute temperature in Fahrenheit

Potential energy lost (mgh) is converted into heat (ms deltaT). Using g = 9.8 m/s^2, mgh = m * 30.6 * 4.184 * deltaT (converting cal to Joules). The mass cancels out, leading to deltaT = (9.8 * 100) / (30.6 * 4.184) approx 7.65 C.

Heat is a form of energy in transit between systems due to a temperature difference; it is not a state function or a property contained within a body. Therefore, saying a body 'contains' heat is physically incorrect regardless of its state.

$dq/dt = [(AK)/2x][T2-T1] = 20/4 = 5.$

 $Therefore ( AK/x)(T2-T1) = 10$

When they are one above the other,

$dq/dt = 2Ak/x][T2-T1] =20/t$

Therefore$t = 2\times10  = 20/t$

Therefore$ t = 1 min$

Applying the formula