10th Class Science Electricity and Circuits Question Bank Electricity

  • question_answer
    The current flowing through 3 ohm resistor is 0.8 ampere, the potential drop across the 4 ohm resistor is                  

    A)  \[1.6\,\,V\]                       

    B)  \[2.4\,\,V\]

    C)  \[4.8\,\,V\]         

    D)         \[9.6\,\,V\]

    Correct Answer: C

    Solution :

     In such networks always begin with the resistor about which two information?s (out of\[R,\,\,V,\,\,I\]) are given, to calculate its third information. So, the voltage across the \[3\Omega \] resistor                 \[=3\times 0.8=2.4\]volts This is also the voltage across the \[6\Omega \] resistor connected in parallel. Now we know, two things about this resistor, so we will calculate its third variable. \[I=\frac{V}{R}=\frac{2.4}{6}=0.4\,\,Amp\] (In parallel branch of twice the resistance, the current can directly be said to be half). Now, the total current through the \[4\Omega \] resistor\[=0.8+0.4=1.2\,\,Amp\] Now, voltage across it,\[V=IR=4\times 1.2=4.8\]


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