Tag: heat exchange

Questions Related to heat exchange

When in thermal contact, the quantity of heat lost by the hotter body is ...... the amount of heat gained by the colder body. (neglect loss of heat due to convection & radiation)

physics measurement and effects of heat heat exchange calorimeter measuring thermal quantities by the method of mixtures

  1. Equal to

  2. Greater than

  3. Less than

  4. Cannot say

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Correct Option: A
Explanation:
When in thermal contact, the quantity of heat lost by the hotter body is equal to the amount of heat gained by the colder body. (neglect loss of heat due to convection & radiation)
This is the principle of calorimetry.

Bunty mixed 440 gm of ice at $0^{\circ}C$ with 540 gm of water at $80^{\circ} C$ in a bowl. Then what would remain after sometime in the bowl?

physics measurement and effects of heat heat exchange calorimeter measuring thermal quantities by the method of mixtures

  1. only ice

  2. only water

  3. ice and water in same amount

  4. ice and water will vapourise

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Correct Option: B
Explanation:

Energy for ice= mL=440(336)= 147840 J
Energy in water= mc$\theta$= 540(80)(4.2)= 181440J

Since, water has more energy, the ice will completely melt while the temperature of water will decrease.
so only ice remains.

The quantity of heat required to raise the temperature of 2000 g of water from 10$^o$C to 50$^o$C is

physics measurement and effects of heat heat exchange calorimeter measuring thermal quantities by the method of mixtures

  1. 80 cal

  2. 80,000 cal

  3. 8000 cal

  4. none of these

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Correct Option: B
Explanation:

Heat required $=mS\triangle T \ =2000\times 1\times (50-10) \ =80000cal$

The quantity/ quantities that does/do not have mass in its/their dimensions is/are

physics measurement and effects of heat heat exchange calorimeter measuring thermal quantities by the method of mixtures

  1. Specific heat

  2. Latent heat

  3. Electrical potential difference

  4. Electrical resistance

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Correct Option: C,D
Explanation:

Specific heat- $J/kg^oC$
Latent Heat- J/kg
Electrical potential difference- J/coulumb
Electrical resistance- ohm
 Hence, option C and D are correct

When 60 calories of heat are supplied to 15 g of water, the rise in temperature is

physics measurement and effects of heat heat exchange calorimeter measuring thermal quantities by the method of mixtures

  1. $75^{\circ}C$

  2. $90^{\circ}C$

  3. $4^{\circ}C $

  4. $0.25^{\circ}C$

Show answer
Correct Option: C
Explanation:

$Heat = m S \Delta T$
$\Rightarrow 60=15\times 1\times\triangle T \ \Rightarrow \triangle T=4^oC$

Calorimeters are generally made of

physics measurement and effects of heat heat exchange calorimeter measuring thermal quantities by the method of mixtures

  1. copper

  2. brass

  3. aluminium

  4. zinc

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Correct Option: A
Explanation:
Calorimeters is made of copper because:
1) Copper has low specific heat capacity and thus it reaches equilibrium temperature quickly by absorbing small amount of heat.

2) Cu is highly malleable and hence very thin box of small mass can be made, thus decreasing heat capacity of box.

3) Cu is good conductor of heat.

On which law does the study of calorimetry based?

physics measurement and effects of heat heat exchange calorimeter measuring thermal quantities by the method of mixtures

  1. Joule's law

  2. Law of conservation of energy

  3. Law of Kinetic energy

  4. None

Show answer
Correct Option: B
Explanation:

Principle of calorimetry states that heat lost by a hotter body = heat gained by a colder body, therefore in calorimetry, total heat energy of the system remains constant, which is the law of conservation of energy . 

When 60 calories of heat are supplied to 15 g of water, the rise in temperature is

physics measurement and effects of heat heat exchange calorimeter measuring thermal quantities by the method of mixtures

  1. $75^\circ C$

  2. $900^\circ C$

  3. $4^\circ C$

  4. $0.25^\circ C$

Show answer
Correct Option: C
Explanation:

We know that, $heat=mass\times specific \;heat\times change\;in\;temperature \ \Rightarrow 60=15\times 1\times \triangle T \ \Rightarrow \triangle T=4^oC$

A thermos bottle containing coffee is vigorously shaken. If the coffee is considered as a system, then the temperature of the coffee will 

physics measurement and effects of heat heat exchange calorimeter measuring thermal quantities by the method of mixtures

  1. increase slightly

  2. fall

  3. remain the same

  4. never be determined

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Correct Option: A
Explanation:
A thermoflask is closed system, so no heat energy added to system i.e. $\triangle \theta=0$
Work is done on the system by shaking it against viscous force. Hence $\triangle w=-ve$
Internal energy, $\triangle U=\triangle \theta - \triangle w=0-(-\triangle w) \\ \Rightarrow \triangle U=+\triangle w$
$\because \triangle U\; is\; +ve$ So there is increase in temperature due to rise in internal enrgy.

The branch of physics that deals with the measurement of heat energy is known as

physics measurement and effects of heat heat exchange calorimeter measuring thermal quantities by the method of mixtures

  1. Fermentation

  2. Latent heat

  3. Calorimetry

  4. Hidden heat

Show answer
Correct Option: C
Explanation:

Calorimetry is the branch of physics which deals with the measurement of heat energy. Calorimetry is one of the methods for the determination of specific heats or latent heats of the substances.