CBSE Class 10 Science 2015 Term I Set 2

Question : 14 of 36

Marks: +1, -0

In the given electric circuit if the current flowing through

3 Ω

resistor is

1 {\A}

, find the voltage of the battery and the current

I

drawn from it.

Solution:

E\;=?

I\;=?

R_2\;=3 Ω

I_2\;=1 {\A} (\;\text " Current flowing through "\; {\R}_2)

V_2\;=I_2 R_2=1 × 3=3 \;\text " volts "\;

Resultant resistance of

R_2

and

R_3

R^{'}

\;{1}/{ {\R}^{'}}\;=\;{1}/{ {\R}_2}+\;{1}/{ {\R}_1}=\;{1}/{3}+\;{1}/{6}=\;{2+1}/{6}=\;{3}/{6}=\;{1}/{2}

{\R}^{'}\;=2 Ω

{\V}^{'}\;= {\V}_2=3 \;\text " volts (Voltage across "\; {\R}^{'})

{\I}^{'}\;=?

{\I}^{'}\;=\;{ {\V}^{'}}/{ {\R}^{'}}=\;{3}/{2} {\A}=1.5 {\A}

{\I}^{'}\;= {\I}=1.5 {\A}

Resultant resistance in the circuit

=R

{\R}\;= {\R}_1+ {\R}^{'}=2+2=4 Ω

{\I}\;=\;{3}/{2} {\A}

{\V}\;=?

{\V}\;= {\IR}=\;{3}/{2} × 4=6 \;\text " volts "\;

⇒ \;\; {\E}\;= {\V}=6 \;\text " volts "\;

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