SATHEE: Current Electricity - Result Question 63

Current Electricity - Result Question 63

67. Six similar bulbs are connected as shown in the figure with a DC source of emf E, and zero internal resistance.

The ratio of power consumption by the bulbs when (i) all are glowing and (ii) in the situation when two from section $A$ and one from section $B$ are

glowing, will be:

(a) $4 : 9$

(b) $9 : 4$

(d) $2 : 1$

[2019]

Show Answer

Answer:

Correct Answer: 67. (b)

Solution:

(b) When all bulbs are glowing

Power $(P_{i}) = \frac{E^{2}}{R_{eq}} = \frac{3 E^{2}}{2 R}$

When two from section $A$ and one from section $B$ are glowing, then

$R_{eq} = \frac{R}{2} + R = \frac{3 R}{2}$

Power $(P_{f}) = \frac{2 E^{2}}{3 R}$

Dividing equation (i) by (ii) we get

$\frac{P_{i}}{P_{f}} = \frac{3 E^{2} 3 R}{2 R 2 E^{2}} = 9 : 4$

(a) Given: Charge $Q = a t - b t^{2}$

$∴$ Current $i = \frac{\partial Q}{\partial t} = a - 2 b t$

$for i = 0 \Rightarrow t = \frac{a}{2 b}$

From joule’s law of heating, heat produced $d H = i^{2} R d t$

$H = \int_{0}^{a / 2 b} (a - 2 b t)^{2} R d t$

$H = . \frac{(a - 2 b t)^{3} R}{- 3 \times 2 b} |_{0}^{\frac{a}{2 b}} = \frac{a^{3} R}{6 b}$

Current Electricity - Result Question 63

67. Six similar bulbs are connected as shown in the figure with a DC source of emf E, and zero internal resistance.

Answer:

Engineering Preparation

Medical Preparation

NCERT Books & Solutions

Important Resources

Other Resources

Syllabus

Test Platform

Sample Mock Test

Mentorship

NCERT Exercise Video Solution

Current Electricity - Result Question 63

67. Six similar bulbs are connected as shown in the figure with a DC source of emf E, and zero internal resistance.

Answer:

Engineering Preparation

Medical Preparation

NCERT Books & Solutions

Important Resources

Other Resources

Syllabus

Test Platform

Sample Mock Test

Mentorship

NCERT Exercise Video Solution

Menu