Physics

A fish looking up through the water sees the outside world contained in a circular horizon. If the refractive index of water is $4 / 3$ and the fish is 12cm below the surface of water, the radius of the circle in centimeter is:

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Contributor-Level 9

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2 months ago

Physics Class 11th

At which of the following temperatures does any gas have average molecular kinetic energy double that of at $20^{0} C$ ?

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Contributor-Level 10

Kinetic energy $E ? T$

$\frac{E_{1}}{E_{2}} = \frac{T_{1}}{T_{2}}$

$T_{2} = 2 * 293$

$T_{2} = 586 K = 313^{0} C$

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Physics Thermodynamics

A cannot engine works as a refrigerator between $250 K$ and $300 K$ . It receives $500 c a l$ heat from the reservoir at the lower temperature. The amount of work done in each cycle to operate the refrigerator is nearly

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Physics Physics Mechanical Properties of Solids

Contributor-Level 10

$C O P = \frac{Q_{t}}{W} = \frac{T_{l o w}}{T_{h i g h} - T_{l o w}} = \frac{250}{300 - 250} = 5$

$\frac{Q_{L}}{W} = 5$

$W = \frac{500 * 4.2}{5} 420 J$

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2 months ago

An object of mass $m$ is connected to a wire of length $' l'$ , radius $' r'$ and Young's modulus $' Y'$ as shown in figure. If the object is released from the horizontal position of the wire, then find out the maximum increment in length of the wire.

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Contributor-Level 10

Elongation in the wire is given as

$? I = \frac{F l}{A Y}$

$T_{m a x} = \frac{m v^{2}}{l} + m g$

$T_{m a x} = 3 m g$

$? l_{m a x} = \frac{3 m g l}{π r^{2} Y}$

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An alternating potential V=V₀sin wt is applied across a circuit. As a result the current I=I₀Sin $I = I_{0} sin (ω t - \frac{π}{2})$ flows in it. The power consumed in the circuit per cycle is

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Contributor-Level 9

No power consumed without any resistance.

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Physics Class 11th

A $120 k g$ dolphin decelerates from $15 m / s$ to $7.5 m / s$ in $5 s$ to join another dolphin in play. What average force was exerted to slow the first dolphin if it was moving horizontally? (Assume that gravitational force is balanced by the buoyant force of the water)

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Physics Electromagnetic Induction

Contributor-Level 10

From equation of uniformly accelerated motion

$v = u + a t$

$7.5 = 15 + 5 a$

$a = - 1.5 m / s^{2}$

$n o w F = m a$

$|\overset{?}{F}| = 120 * 1.5$

$= 180 N$

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2 months ago

The current in an inductor is given by $i = 2 + 3 t$ ampere where t is in second. The self?induced emf in it is $9 m V$ ; the energy stored in the inductor at t=1 second is

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Contributor-Level 9

Please find the answer below

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A current 1 flows along the length of an infinitely long, straight and thin?walled pipe. Then:

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The magnetic field at any point inside the pipe is zero

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Two long conductors, separated by a distance d carry current $I_{1}$ and $I_{2}$ in the same direction. They exert a force F on each other. Now the current in one of them is increased to two times and its directions is reversed. The distance is also increased to 3 d. The new value of the force between them is

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Contributor-Level 9

$F \propto \frac{i_{1} i_{2}}{a}$ Since one of the current increase two times

and distance increases three times, so force become $\frac{2}{3}$ times. Also due to the reversal of direction of current force becomes negative.

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2 months ago

A neutral point is obtained at the Centre of a vertical circular coil carrying current. The angle between the plane of the coil and the magnetic meridian is

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