An electric bulb is rated at $200\, V -100\, W$. What is its resistance ? Five such bulbs burn for $4$ hours. What is the electrical energy consumed ? Calculate the cost, if the rate is $50$ paise unit.
An electric bulb is rated at $200\, V -100\, W$. What is its resistance ? Five such bulbs burn for $4$ hours. What is the electrical energy consumed ? Calculate the cost, if the rate is $50$ paise unit.
Given $V =200 V , P =100 W , n=5, E =?$
$(a)$ We know that $P =\frac{ V ^{2}}{ R }$ or $R =\frac{ V ^{2}}{ P },$ therefore, resistance of each bulb is
$R =\frac{ V ^{2}}{ P }=\frac{(200)^{2}}{100}=400 \Omega$
$(b)$ Electrical energy consumed by one bulb in $4$ hours $S$
$=100 \times 4=400 Wh$
Energy consumed by $5$ bulbs in $4$ hours
$=400 \times 5=2000 Wh =2 kW h$
$(c)$ Cost of consumed electricity.
$=2 \times 0.5=$₹ $1$
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Read the following statements carefully and write whether the statement is true or false
$(i)$ The quantity of charge flowing past a point multiplied by time is current.
$(ii)$ The flow of charge through a conducting wire connected to a cell is the result of chemical reaction inside the cell
$(iii)$ The resistivity of all pure metals increases with increase in temperature.
$(iv)$ Ohm's law is a relation between the power used in a circuit to the current and the potential difference.
$(v)$ $A$ series circuit has only one conducting path for the electrons that move through it; a parallel circuit has multiple conducting paths.
$(vi)$ A conducting wire offers resistance to the flow of electrons because electrons repel each other in the wire.