(B) The first law of thermodynamics is generally expressed as $\Delta Q = \Delta U + W_{by}$,where $W_{by}$ is the work done $BY$ the system.In this p

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$\Delta Q = \Delta U - \Delta W$

(B) The first law of thermodynamics is generally expressed as $\Delta Q = \Delta U + W_{by}$,where $W_{by}$ is the work done $BY$ the system.In this problem,$\Delta W$ is defined as the work done $ON$ the system.By sign convention,work done on the system is negative of work done by the system,so $W_{by} = -\Delta W$.Substituting this into the first law equation: $\Delta Q = \Delta U + (-\Delta W)$.Therefore,the correct expression is $\Delta Q = \Delta U - \Delta W$.

Class 11 Physics Thermodynamics First Law of Thermodynamics

Medium

If $\Delta Q$ and $\Delta W$ represent the heat supplied to the system and the work done on the system respectively,then the first law of thermodynamics can be written as,where $\Delta U$ is the change in internal energy.

A
$\Delta Q = \Delta U + \Delta W$
B
$\Delta Q = \Delta U - \Delta W$
C
$\Delta Q = \Delta W - \Delta U$
D
$\Delta Q = - \Delta W - \Delta U$

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Thermodynamics

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First Law of Thermodynamics

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An electric heater supplies heat to a system at a rate of $100 \text{ W}$. If the system performs work at a rate of $75 \text{ J/s}$,then the rate at which internal energy increases will be: (in $\text{ W}$)

MediumNEET 2026

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MediumIIT 2005

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If $\Delta Q$ and $\Delta W$ represent the heat supplied to the system and the work done on the system respectively,then the first law of thermodynamics can be written as,where $\Delta U$ is the change in internal energy.

Similar Questions

Write and explain the first law of thermodynamics.

The volume of one mole of the gas is changed from $V$ to $2V$ at constant pressure $p$. If $\gamma$ is the ratio of specific heats of the gas,what is the change in internal energy of the gas?

An electric heater supplies heat to a system at a rate of $100 \text{ W}$. If the system performs work at a rate of $75 \text{ J/s}$,then the rate at which internal energy increases will be: (in $\text{ W}$)

$A$ thermally insulated rigid container contains an ideal gas heated by a filament of resistance $100 \,\Omega$ through a current of $1 \,A$ for $5 \,min$. The change in internal energy is...... $kJ$.

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