Question:
If W is the energy required to form a soap bubble of radius R, then energy required to increase radius from R to 3R is:
If W is the energy required to form a soap bubble of radius R, then energy required to increase radius from R to 3R is:
Show Hint
Surface energy depends on surface area $\propto r^2$.
Updated On: Jun 17, 2026
- 9W
- 3W
- 8W
- 4W
Show Solution
Verified By Collegedunia
The Correct Option is C
Solution and Explanation
Step 1: Energy of soap bubble is proportional to surface area: \[ E = 2T \cdot 4\pi r^2 = 8\pi Tr^2 \]
Step 2: Given: \[ W = kR^2 \]
Step 3: Energy at radius 3R: \[ E_{3R} = k(3R)^2 = 9kR^2 = 9W \]
Step 4: Required energy increase: \[ \Delta E = 9W - W = 8W \]
Was this answer helpful?
0
0
Top TS EAMCET Physics Questions
- A wooden box lying at rest on an inclined surface of a wet wood is held at static equilibrium by a constant force $F$ applied perpendicular to the incline. If the mass of the box is $1\,kg$, the angle of inclination is $30^{\circ}$ and the coefficient of static friction between the box and the inclined plane is $0.2$, the minimum magnitude of $\vec{F}$ is (Use $ g = 10\,m/s^2$)
- A metre scale made of steel reads accurately at $25^{\circ} C$ . Suppose in an experiment an accuracy of $0.06\, mm$ in $1\,m$ is required, the range of temperature in which the experiment can be performed with this metre scale is (coefficient of linear expansion of steel is $ 11 \times 10^{-6} /^{\circ} \, C$ )
- Consider a solenoid carrying current supplied by a DC source with a constant emf containing iron core inside it. When the core is pulled out of the solenoid, the change in current will
- A parallel beam of light of intensity \(I_0\) is incident on a coated glass plate. If \(25\%\) of the incident light is reflected from the upper surface and \(50\%\) of light is reflected from the lower surface of the glass plate, the ratio of maximum to minimum intensity in the interference region of the reflected light is
- A thermocol box has a total wall area (including the lid) of $1.0 m ^{2}$ and wall thickness of $3 cm$. It is filled with ice at $0^{\circ} C$. If the average temperature outside the box is $30^{\circ} C$ throughout the day, the amount of ice that melts in one day is [Use $K_{\text {thermocol }}=0.03 W / mK$ $.L_{\text {fusion (ice) }}=3.00 \times 10^{5} J / kg ]$
View More Questions
Top TS EAMCET Mechanical Properties of Fluids Questions
- An incompressible fluid is flowing through a tube of uniform cross-section. The increase in the power of the pump required to double the rate of flow is:
- The ratio of the lengths of two wires A and B made of same material is 2:1. The diameter of wire A is twice the diameter of wire B. If both the wires are stretched by same tension, the ratio of the energies stored in wires A and B is:
- Two spherical rain drops of radii in the ratio 4:5 are falling vertically through air. The ratio of the terminal velocities of the rain drops is:
- A liquid drop of diameter 2 mm breaks into 125 identical drops, then the change in the surface energy is:
- If \(W_1\) is the work done in increasing the radius of a soap bubble from 'r' to '2r' and \(W_2\) is the work done in increasing the radius of the soap bubble from '2r' to '3r', then \(W_1: W_2 =\)
View More Questions
Top TS EAMCET Questions
- A bag contains $5$ red balls, $3$ black balls and $4$ white balls are drawn at random. The probability that they are not of same colour is
- If $cosec\, \theta - \cot \theta = 2017$, then quadrant in which $\theta $ lies is
- If $a$ is a unit vector, then $| a \times \hat{ i }|^{2}+| a \times \hat{ j }|^{2}+| a \times \hat{ k }|^{2}=$
- $A$ straight line makes an intercept on the $Y$-axis twice as long as that on $X$-axis and is at a unit distance from the origin. Then the line is represented by the equations
- Let $S$ and $S'$ be the foci of an ellipse and B be one end of its minor axis. If $SBS'$ is an isosceles right angled triangle then the eccentricity of the ellipse is
View More Questions