
The internal resistance of a primary cell is 4 Ω. It generates a current of 0.2 A in an external resistance of 21Ω. The rate of chemical energy consumed in providing the current is
\[\begin{align}
& \text{A}\text{. }\!\!~\!\!\text{ 1 J/s} \\
& \text{B}\text{. }\!\!~\!\!\text{ }\!\!~\!\!\text{ 5 J/s} \\
& \text{C}\text{. }\!\!~\!\!\text{ }\!\!~\!\!\text{ 0}\text{.42 J/s} \\
& \text{D}\text{. }\!\!~\!\!\text{ 0}\text{.8 J/s} \\
\end{align}\]
Answer
501.3k+ views
Hint: The rate of chemical energy consumed is nothing but power. Use the formula of power. Many forms of power are available using any formula which will give you relation between current and resistance, since values and current resistance are available. Use Kirchhoff’s voltage and current law.
Formula used: $\text{power=(current)}\times \text{(current)}\times \text{(resistance)}$
Complete step by step answer:
First, understand what the question wants to convey.
Consider a circuit having cells and resistance connected to each other by wires. The cell is nothing but a device. Devices have their internal resistance. So the cell has resistance 4ohm. 0.2 is the current passing through the circuit. While external resistance that is the resistance which we have applied is 21 ohm.
Aim: The rate of chemical energy consumed in providing the current which is nothing but power.
We know that,
$\text{voltage=current }\!\!\times\!\!\text{ resistance}$
Mathematically is given by,
$V=I\times R--------\left( 1 \right)$
Use the formula of power I.e. The rate of chemical energy consumed in providing the current,
So by conservation of energy.
Heat energy produced per sec= Power
$\text{power=(current)}\times \text{(current)}\times \text{(resistance)}$
$\begin{align}
& \text{power(P)=}{{\text{I}}^{\text{2}}}\text{(R+r)} \\
& \text{power=0}\text{.2 }\!\!\times\!\!\text{ 0}\text{.2 }\!\!\times\!\!\text{ (21+4)} \\
& \text{power=1J}{{\text{s}}^{\text{-1}}} \\
\end{align}$
(Where r is the internal resistance and R is the external resistance)
Hence the rate of chemical energy consumed in providing the current is $\text{1J}{{\text{s}}^{\text{-1}}}$.
Hence, the correct answer is option A .
Note:
You can get the idea of what to find out in question by looking at the options. Internal resistance is the resistance which the device itself has while manufacturing. External resistance is what we apply to the circuit.
Formula used: $\text{power=(current)}\times \text{(current)}\times \text{(resistance)}$
Complete step by step answer:
First, understand what the question wants to convey.
Consider a circuit having cells and resistance connected to each other by wires. The cell is nothing but a device. Devices have their internal resistance. So the cell has resistance 4ohm. 0.2 is the current passing through the circuit. While external resistance that is the resistance which we have applied is 21 ohm.
Aim: The rate of chemical energy consumed in providing the current which is nothing but power.
We know that,
$\text{voltage=current }\!\!\times\!\!\text{ resistance}$
Mathematically is given by,
$V=I\times R--------\left( 1 \right)$
Use the formula of power I.e. The rate of chemical energy consumed in providing the current,
So by conservation of energy.
Heat energy produced per sec= Power
$\text{power=(current)}\times \text{(current)}\times \text{(resistance)}$
$\begin{align}
& \text{power(P)=}{{\text{I}}^{\text{2}}}\text{(R+r)} \\
& \text{power=0}\text{.2 }\!\!\times\!\!\text{ 0}\text{.2 }\!\!\times\!\!\text{ (21+4)} \\
& \text{power=1J}{{\text{s}}^{\text{-1}}} \\
\end{align}$
(Where r is the internal resistance and R is the external resistance)
Hence the rate of chemical energy consumed in providing the current is $\text{1J}{{\text{s}}^{\text{-1}}}$.
Hence, the correct answer is option A .
Note:
You can get the idea of what to find out in question by looking at the options. Internal resistance is the resistance which the device itself has while manufacturing. External resistance is what we apply to the circuit.
Recently Updated Pages
Express the following as a fraction and simplify a class 7 maths CBSE

The length and width of a rectangle are in ratio of class 7 maths CBSE

The ratio of the income to the expenditure of a family class 7 maths CBSE

How do you write 025 million in scientific notatio class 7 maths CBSE

How do you convert 295 meters per second to kilometers class 7 maths CBSE

Write the following in Roman numerals 25819 class 7 maths CBSE

Trending doubts
Give 10 examples of unisexual and bisexual flowers

Draw a labelled sketch of the human eye class 12 physics CBSE

Differentiate between homogeneous and heterogeneous class 12 chemistry CBSE

Differentiate between insitu conservation and exsitu class 12 biology CBSE

What are the major means of transport Explain each class 12 social science CBSE

Franz thinks Will they make them sing in German even class 12 english CBSE
