Answer
Verified
434.7k+ views
Hint: We know that, when we connect the resistors parallel to each other, the equivalent resistance decreases. Also, in parallel circuits, the voltage in both arms remains the same. Use Ohm’s law to determine the current in the resistors.
Formula used:
\[I = \dfrac{V}{R}\], where, V is the voltage and R is the resistance of the circuit.
Complete step by step answer:
We know that, when we connect the resistors parallel to each other, the equivalent resistance decreases.
According to Ohm’s law, the current in the circuit is defined as,
\[I = \dfrac{V}{R}\], where, V is the voltage and R is the resistance of the circuit.
From the above expression, we can say that the current in the circuit is inversely proportional to the resistance.
Therefore, the current in the electric meter will be the maximum when the resistance is the minimum. The minimum resistance can be obtained by connecting the three resistors of \[12\,\Omega \] in parallel.
The equivalent resistance of three \[12\,\Omega \] resistors is,
\[\dfrac{1}{{{R_{eq}}}} = \dfrac{1}{{12}} + \dfrac{1}{{12}} + \dfrac{1}{{12}}\]
\[ \Rightarrow \dfrac{1}{{{R_{eq}}}} = \dfrac{3}{{12}} = \dfrac{1}{4}\]
\[ \Rightarrow {R_{eq}} = 4\,\Omega \]
The voltage in the electrical meter when the internal resistance is \[20\,\Omega \] is,
\[V = {I_L}{R_i}\] …… (1)
The voltage across the resistance \[{R_{eq}} = 4\,\Omega \] is,
\[V = {I_2}{R_{eq}}\] …… (2)
Since the voltage in the parallel circuit does not change, we can write,
\[{I_L}{R_i} = {I_2}{R_{eq}}\]
\[ \Rightarrow {I_2} = \dfrac{{{I_L}{R_i}}}{{{R_{eq}}}}\]
Substitute \[1\,mA\] for \[{I_L}\], \[20\,\Omega \] for \[{R_L}\] and \[4\,\Omega \] for \[{R_{eq}}\] in the above equation.
\[{I_2} = \dfrac{{\left( {1\,mA} \right)\left( {20\,\Omega } \right)}}{{4\,\Omega }}\]
\[ \Rightarrow {I_2} = 5\,mA\]
Therefore, the maximum current that can flow through the electric meter is,
\[{I_{\max }} = 1\,mA + 5\,mA\]
\[ \Rightarrow {I_{\max }} = 6\,mA\]
So, the correct answer is “Option C”.
Note:
Students should remember the change in voltage and current in the series and parallel combination. The internal resistance of the electrical resistance is due to the resistance of the electric component in the circuit. This internal resistance is usually neglected in calculations.
Formula used:
\[I = \dfrac{V}{R}\], where, V is the voltage and R is the resistance of the circuit.
Complete step by step answer:
We know that, when we connect the resistors parallel to each other, the equivalent resistance decreases.
According to Ohm’s law, the current in the circuit is defined as,
\[I = \dfrac{V}{R}\], where, V is the voltage and R is the resistance of the circuit.
From the above expression, we can say that the current in the circuit is inversely proportional to the resistance.
Therefore, the current in the electric meter will be the maximum when the resistance is the minimum. The minimum resistance can be obtained by connecting the three resistors of \[12\,\Omega \] in parallel.
The equivalent resistance of three \[12\,\Omega \] resistors is,
\[\dfrac{1}{{{R_{eq}}}} = \dfrac{1}{{12}} + \dfrac{1}{{12}} + \dfrac{1}{{12}}\]
\[ \Rightarrow \dfrac{1}{{{R_{eq}}}} = \dfrac{3}{{12}} = \dfrac{1}{4}\]
\[ \Rightarrow {R_{eq}} = 4\,\Omega \]
The voltage in the electrical meter when the internal resistance is \[20\,\Omega \] is,
\[V = {I_L}{R_i}\] …… (1)
The voltage across the resistance \[{R_{eq}} = 4\,\Omega \] is,
\[V = {I_2}{R_{eq}}\] …… (2)
Since the voltage in the parallel circuit does not change, we can write,
\[{I_L}{R_i} = {I_2}{R_{eq}}\]
\[ \Rightarrow {I_2} = \dfrac{{{I_L}{R_i}}}{{{R_{eq}}}}\]
Substitute \[1\,mA\] for \[{I_L}\], \[20\,\Omega \] for \[{R_L}\] and \[4\,\Omega \] for \[{R_{eq}}\] in the above equation.
\[{I_2} = \dfrac{{\left( {1\,mA} \right)\left( {20\,\Omega } \right)}}{{4\,\Omega }}\]
\[ \Rightarrow {I_2} = 5\,mA\]
Therefore, the maximum current that can flow through the electric meter is,
\[{I_{\max }} = 1\,mA + 5\,mA\]
\[ \Rightarrow {I_{\max }} = 6\,mA\]
So, the correct answer is “Option C”.
Note:
Students should remember the change in voltage and current in the series and parallel combination. The internal resistance of the electrical resistance is due to the resistance of the electric component in the circuit. This internal resistance is usually neglected in calculations.
Recently Updated Pages
How many sigma and pi bonds are present in HCequiv class 11 chemistry CBSE
Mark and label the given geoinformation on the outline class 11 social science CBSE
When people say No pun intended what does that mea class 8 english CBSE
Name the states which share their boundary with Indias class 9 social science CBSE
Give an account of the Northern Plains of India class 9 social science CBSE
Change the following sentences into negative and interrogative class 10 english CBSE
Trending doubts
Which are the Top 10 Largest Countries of the World?
Difference between Prokaryotic cell and Eukaryotic class 11 biology CBSE
Fill the blanks with the suitable prepositions 1 The class 9 english CBSE
Difference Between Plant Cell and Animal Cell
Give 10 examples for herbs , shrubs , climbers , creepers
Differentiate between homogeneous and heterogeneous class 12 chemistry CBSE
The Equation xxx + 2 is Satisfied when x is Equal to Class 10 Maths
How do you graph the function fx 4x class 9 maths CBSE
Write a letter to the principal requesting him to grant class 10 english CBSE