Question 689: Current Electricity

Question

In the circuit shown, the current through the 4 $$\Omega $$ resistor is 1 amp when the points P and M are connected to a d.c. voltage source. The potential difference betwen the points M and N is

Accepted Answer

As the P.D. between 4 $$\Omega $$ and 3 $$\Omega $$ (in parallel), are the same,
4 ÃÂ 1 amp = 3 ÃÂ i
1
$$ \Rightarrow {i_1} = {4 \over 3}A$$
Total resistance of 4 $$\Omega $$ and 3 $$\Omega $$ = 12/7 $$\Omega $$.
Current in MQP (upper one) = $$1 + {4 \over 3} = {7 \over 3}A$$
$$ 	herefore $$ $$P.D. = {{12} \over 7} 	imes {7 \over 3} = 4V$$
Current in MNP = $${4 \over {1.25}} = {{4 	imes 4} \over 5} = {{16} \over 5}A$$
$$ 	herefore $$ P.D. across $$1\Omega  = {{16} \over 5}A 	imes 1\Omega  = {{16} \over 5}volt$$
$$ \Rightarrow $$ P.D. across 1$$\Omega$$  = 3.2 volt.

Answer

0.5 volt

Answer

3.2 volt

Answer

1.5 volt

Answer

1.0 volt

Current Electricity

In the circuit shown, the current through the 4 $\Omega $ resistor is 1 amp when the points P and M are connected to a d.c. voltage source. The potential difference betwen the points M and N is

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