NCERT Solutions · Class 10 Science Electricity

A piece of wire of resistance R is cut into five equal parts. These parts are then connected in parallel. If the equivalent resistance of this combination is R′, then the ratio R/R′ is –

$\displaystyle 1$/$\displaystyle 25$

$\displaystyle 1$/$\displaystyle 5$

$\displaystyle 5$ (d) $\displaystyle 25$

Which of the following terms does not represent electrical power in a circuit?

I2R

IR2

VI

V2/R

An electric bulb is rated $\displaystyle 220$ V and $\displaystyle 100$ W. When it is operated on $\displaystyle 110$ V, the power consumed will be –

$\displaystyle 100$ W

$\displaystyle 75$ W

$\displaystyle 50$ W

$\displaystyle 25$ W

Two conducting wires of the same material and of equal lengths and equal diameters are first connected in series and then parallel in a circuit across the same potential difference. The ratio of heat produced in series and parallel combinations would be –

$\displaystyle 1$:$\displaystyle 2$

$\displaystyle 2$:$\displaystyle 1$

$\displaystyle 1$:$\displaystyle 4$

$\displaystyle 4$:$\displaystyle 1$