The resistors $R_1 , R_2 , R_3$ and $R_4$ in the figure given below are all equal in value.
What would you expect the voltmeters $A, B$ and $C$ to read assuming that the connecting wires in the circuit have negligible resistance?
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$R_{eq} = R + R + R + R = 4R$ ohm
Total current in the circuit, $\text{I}=\frac{\text{V}}{\text{R}}=\frac{12}{4\text{R}}=\frac{3}{\text{R}}$
Reading of voltmeter $A =$ Voltage across $\text{R}_1=\text{I}\times\text{R}_1=\frac{3}{\text{R}}\times\text{R}=3\text{V}$
Reading of voltmeter $B =$ Voltage across $\text{R}_2=\text{I}\times\text{R}_2=\frac{3}{\text{R}}\times\text{R}=3\text{V}$
Reading of voltmeter $C =$ Voltage across the series combination of $R_3$ and $R_4$ $=\text{I}\times(\text{R}_3+\text{R}_4)=\frac{3}{\text{R}}\times2\text{R}=6\text{V}$
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An electric iron is connected to the mains power supply of $220V$. When the electric iron is adjusted at ‘minimum heating’ it consumes a power of $360W$ but at ‘maximum heating’ it takes a power of $840W$. Calculate the current and resistance in each case.
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$\begin{matrix}\text{P}&6.84\times10^{-8}\Omega\text{m}\\\text{Q}&1.70\times10^{-8}\Omega\text{m}\\\text{R}&1.0\times10^{15}\Omega\text{m}\\\text{S}&11.0\times10^{-7}\Omega\text{m}\end{matrix}$
Which material will you use for making:
A resistor of 8 ohms is connected in parallel with another resistor X. The resultant resistance of the combination is 4.8 ohms. What is the value of the resistor X?