An electric bulb is rated $$220\,volt - 100\,watt.$$ The power consumed by it when operated on $$110\,volt$$ will be
A.
$$75\,watt$$
B.
$$40\,watt$$
C.
$$25\,watt$$
D.
$$50\,watt$$
Answer :
$$25\,watt$$
Solution :
The resistance of the bulb is $$R = \frac{{{V^2}}}{P} = \frac{{{{\left( {220} \right)}^2}}}{{100}}$$
The power consumed when operated at $$110\,V$$ is
$$P = \frac{{{{\left( {110} \right)}^2}}}{{\frac{{{{\left( {220} \right)}^2}}}{{100}}}} = \frac{{100}}{4} = 25W$$
Releted MCQ Question on Electrostatics and Magnetism >> Electric Current
Releted Question 1
The temperature coefficient of resistance of a wire is 0.00125 per $$^ \circ C$$ At $$300\,K,$$ its resistance is $$1\,ohm.$$ This resistance of the wire will be $$2\,ohm$$ at.
The electrostatic field due to a point charge depends on the distance $$r$$ as $$\frac{1}{{{r^2}}}.$$ Indicate which of the following quantities shows same dependence on $$r.$$
A.
Intensity of light from a point source.
B.
Electrostatic potential due to a point charge.
C.
Electrostatic potential at a distance r from the centre of a charged metallic sphere. Given $$r$$ < radius of the sphere.