The figure shows three similar lamps L_1, L_2 | vedclass

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Question

(B) Let the resistance of each lamp be $R$. Initially,$L_2$ and $L_3$ are in parallel,and their equivalent resistance is $R_p = \frac{R 	imes R}{R +

Vedclass · Accepted Answer

Brilliance of $L_1$ decreases and that of $L_2$ increases

Vedclass · Answer

(B) Let the resistance of each lamp be $R$. Initially,$L_2$ and $L_3$ are in parallel,and their equivalent resistance is $R_p = \frac{R 	imes R}{R + R} = \frac{R}{2}$.This combination is in series with $L_1$. The total resistance of the circuit is $R_{eq} = R + \frac{R}{2} = \frac{3R}{2}$.The total current from the source is $I = \frac{E}{R_{eq}} = \frac{2E}{3R}$.This current $I$ flows through $L_1$. The voltage across $L_1$ is $V_1 = I 	imes R = \frac{2E}{3}$. The voltage across the parallel combination ($L_2$ and $L_3$) is $V_p = I 	imes \frac{R}{2} = \frac{E}{3}$.When $L_3$ fuses,it acts as an open circuit. The circuit now consists of $L_1$ and $L_2$ in series.The new total resistance is $R'_{eq} = R + R = 2R$.The new current in the circuit is $I' = \frac{E}{2R}$.For $L_1$: The new current $I' = \frac{E}{2R}$ is less than the initial current $I = \frac{2E}{3R} = \frac{0.66E}{R}$. Thus,the brilliance of $L_1$ decreases.For $L_2$: The new voltage across $L_2$ is $V'_2 = I' 	imes R = \frac{E}{2} = 0.5E$. The initial voltage across $L_2$ was $V_p = \frac{E}{3} \approx 0.33E$. Since $0.5E > 0.33E$,the voltage across $L_2$ increases,so the brilliance of $L_2$ increases.

The figure shows three similar lamps $L_1, L_2$,and $L_3$ connected across a power supply. If the lamp $L_3$ fuses,how will the light emitted by $L_1$ and $L_2$ change?

Similar Questions

The ratio of the magnetic field at the centre of a current-carrying circular wire and the magnetic field at the centre of a square coil made from the same length of wire will be

$A$ transistor is used as a common emitter amplifier with a load resistance of $2 \ k\Omega$. The input resistance is $150 \ \Omega$. Base current is changed by $20 \ \mu A$,which results in a change in collector current by $1.5 \ mA$. The voltage gain of the amplifier is

The isothermal Bulk modulus of an ideal gas at pressure $P$ is

Which one of the following is an example of cleistogamy?

The component of vector $\overrightarrow{A} = a_x \hat{i} + a_y \hat{j} + a_z \hat{k}$ along the direction of $\hat{i} - \hat{j}$ is

Vedclass Test Series

Exam Paper Generator

Online Exam Module