Question 465: Current Electricity

Question

In an electric circuit, a cell of certain emf provides a potential difference of 1.25 V across a load resistance of 5$$\Omega$$. However, it provides a potential difference of 1 V across a load resistance of 2$$\Omega$$. The emf of the cell is given by $${x \over {10}}V$$. Then the value of x is ______________.

Accepted Answer

In case (a) $$\varepsilon  = {{1.25} \over 5}(5 + r)$$
$$ \Rightarrow 4\varepsilon  = 5 + r$$ ..... (1)
In case (b), $$\varepsilon  = {1 \over 2}(2 + r)$$
$$ \Rightarrow 2\varepsilon  = 2 + r$$ ..... (2)
From equation (1) & (2)
$$2\varepsilon  = 3 \Rightarrow \varepsilon  = 1.5$$
or x = 15

Current Electricity

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