A heater coil connected to a supply of a $220\, V$ is dissipating some power ${P_1}.$ The coil is cut into half and the two halves are connected in parallel. The heater now dissipates a power ${P_2}.$ The ratio of power ${P_1}\,\,:\,\,{P_2}$ is
A$2:1$
B$1:2$
C$1:4$
D$4:1$
Medium
Download our app for free and get started
C$1:4$
c (c) $P = \frac{{{V^2}}}{R}$. If resistance of heater coil is $R$, then resistance of parallel combination of two halves will be $\frac{R}{4}$
So $\frac{{{P_1}}}{{{P_2}}} = \frac{{{R_2}}}{{{R_1}}} = \frac{{R/4}}{R} = \frac{1}{4}$
Download our app
and get started for free
Experience the future of education. Simply download our apps or reach out to us for more information. Let's shape the future of learning together!No signup needed.*
In the circuit shown, current through $R_2$ is zero. If $R_4 = 2\,\Omega $ and $R_3 = 4\,\Omega $ , current through $R_3$ will be ................. $\mathrm{A}$
An electric toaster has resistance of $60\ \Omega$ at room temperature $\left(27^{\circ} \mathrm{C}\right)$. The toaster is connected to a $220 \mathrm{~V}$ supply. If the current flowing through it reaches $2.75 \mathrm{~A}$, the temperature attained by toaster is around : (if $\alpha=2 \times 10^{-4} /{ }^{\circ} \mathrm{C}$ )
If two bulbs of wattage $25$ and $100$ respectively each rated at $220\, volt$ are connected in series with the supply of $440\, volt$, then which bulbs will fuse
A copper wire has a square cross-section, $2.0\, mm$ on a side. It carries a current of $8\, A$ and the density of free electrons is $8 \times {10^{28}}\,{m^{ - 3}}$. The drift speed of electrons is equal to