Two heater wires of equal length are first connected in series and then in parallel. The ratio of heat produced in the two cases is
A$2:1$
B$1:2$
C$4:1$
D$1:4$
AIIMS 2000, Medium
Download our app for free and get started
D$1:4$
d (d) Power consumed means heat produced.
For constant potential difference ${P_{{\rm{consumed}}}} = {\rm{Heat}} \propto \frac{1}{{{R_{eq}}}}$
$\therefore \frac{{{H_1}}}{{{H_2}}} = \frac{{{R_2}}}{{{R_1}}} = \frac{{R/2}}{{2R}} = \frac{1}{4}$
(Since ${R_2} = \frac{{R.R}}{{R + R}} = \frac{R}{2}$and ${R_1} = R + R = 2R)$
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.*
The given figure represents an arrangement of potentiometer for the calculation of internal resistance $(r)$ of the unknown battery $(E)$. The balance length is $70.0\, cm$ with the key opened and $60.0\,cm$ with the key closed. $R$ is $132.40 \Omega $. The internal resistance $(r)$ of the unknown cell will be.......$\Omega$ (Given $E_o > E$) :-
In the circuit shown in figure reading of voltmeter is $V_1$ when only $S_1$ is closed, reading of voltmeter is $ V_2$ when only $S_2$ is closed and reading of voltmeter is $V_3$ when both $S_1$ and $S_2$ are closed. Then
There are $0.8 \times 10^{23}$ free electrons $/ cm^3$ in copper. If $0.2\, A $ current is flowing is copper wire, then the drift velocity of electrons will be, if the cross sectional area of wire is $0.01 \,cm^2$
Two cylindrical rods of uniform crosssection area $A$ and $2A$, having free electrons per unit volume $2n$ and $n$ respectively are joined in series. A current $I$ flows through them in steady state. Then the ratio of drift velocity of free electron in left rod to drift velocity of electron in the right rod is $\left( {\frac{{{v_L}}}{{{v_R}}}} \right)$
An electric iron draws $5\, amp$, a $TV$ set draws $3\, amp$ and refrigerator draws $2\, amp$ from a $220\, volt$ main line. The three appliances are connected in parallel. If all the three are operating at the same time, the fuse used may be of ............. $amp$