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Class 12th Physics

The magnetic moment of an electron (e) revolving in an orbit around nucleus with an orbital angular momentum is given by:

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Vishal Baghel

Contributor-Level 10

Kindly consider the following answer

$\vec{μ} = - \frac{e}{2 m} \vec{L}$

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Class 12th Atoms

The momentum of an electron revolving in nth orbit is given by:

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Vishal Baghel

Contributor-Level 10

mvr = $\frac{n h}{2 π}$ $\frac{}{}$

So momentum (mv) = $\frac{n h}{2 π r}$

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Class 12th Maths

A plane E is perpendicular to the two planes 2x – 2y + z = 0 and x – y + 2z = 4, and passes through the point P(1, -1, 1). If the distance of the plane E from the point Q(a, a, 2) is $3 \sqrt[]{2},$ then (PQ)² is equal to

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Payal Gupta

Contributor-Level 10

First plane, P₁ = 2x – 2y + z = 0,

normal vector $\equiv n_{1} = (2, - 2, 1)$

Second plane, P₂ = x – y + 2z = 4,

normal vector $\equiv n_{2} = (1, - 1, 2)$

Plane perpendicular to P₁ and P₂ will have normal vector n₃ where n₃ = (n₁* n₂)

Hence,

n₃ = (3, 0)

Distance PQ

$= \sqrt[]{21} \Rightarrow {(P Q)}^{2} = 21$

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Class 12th Physics

A metal exposed to light of wavelength 800nm and emits photoelectrons with a certain kinetic energy. The maximum kinetic energy of photo-electron doubles when light of wavelength 500nm is used. The work function of the metal is: (Take hc = 1230 eV –nm).

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Vishal Baghel

Contributor-Level 10

$_{} \frac{}{}$ $K . E_{1} = \frac{1230}{800} - ?$ - (i)

$_{}_{} \frac{}{}$ $K . E_{2} = 2 K . E_{1} = \frac{1230}{500} - ?$ - (ii)

from (i) & (ii)

$? = 0.615$ ev

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Class 12th Physics

A thin lens made of glass (refractive index $= 1.5$ ) of focal length $f = 16 c m$ is immersed in a liquid of refractive index 1.42. If its focal length in liquid is $f_{l}$ , then the ratio $f_{l}$ /f is closest to the integer:

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alok kumar singh

Contributor-Level 10

$\frac{1}{f} = (μ_{g} - 1) (\frac{1}{R_{1}} - \frac{1}{R_{2}})$

$\frac{1}{f_{l}} = (\frac{μ_{g}}{μ_{l}} - 1) (\frac{1}{R_{1}} - \frac{1}{R_{2}})$

(i) $\frac{f_{l}}{f} = \frac{μ_{g} - 1}{\frac{μ_{g}}{μ_{l}} - 1} = \frac{1.5 - 1}{\frac{1.5}{1.41} - 1} = 8.875 \approx 9$

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Class 12th Physics

Time taken by light to travel in two different materials A and B refractive indices $μ_{A} a n d μ_{B}$ of same thickness is $t_{1} a n d t_{2}$ respectively. It $t_{2} - t_{1} = 5 * 1 0^{- 10} s$ and the ratio of $μ_{A} t o μ_{B}$ 1 : 2. Then, the thickness of material, in meter is: (Given $υ_{A} a n d υ_{B}$ are velocities of light in A and B materials respectively.)

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Vishal Baghel

Contributor-Level 10

$\frac{μ_{A}}{μ_{B}} = \frac{C / v_{A}}{C / v_{B}} = \frac{v_{B}}{v_{A}} = \frac{1}{2}$

Let the thickness is d

$d = \frac{5 * 1 0^{- 10} * v_{A} v_{B}}{v_{A} - v_{B}}$

d = 5 * 10^-10 * v_A

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Class 12th Chemistry

Which of the following methods are not used to refine any metal?

(A). Liquation

(B). Calcination

(C). Electrolysis

(D). Leaching

(E). Distillation

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alok kumar singh

Contributor-Level 10

Calcination and leaching are the methods of concentration of ores and not that of refining.

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Class 12th Physics

Which of the following statement is correct?

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Vishal Baghel

Contributor-Level 10

In primary rainbow, red colour is at top and violet is at bottom.

Intensity of secondary rainbow is less in comparison to primary rainbow.

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Class 12th Dual Nature of Radiation and Matter

An electron (of mass $m$ ) and a photon have the same energy $E$ in the range of a few eV. The ratio of the de-Broglie wavelength associated with the electron and the wavelength of the photon is ( $c =$ speed of light in vacuum)

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alok kumar singh

Contributor-Level 10

$λ_{electron} = \frac{h}{\sqrt[]{2 m E}} \frac{λ_{electron}}{λ_{photon}} = \frac{1}{c} \sqrt[]{\frac{E}{2 m}}$

$λ_{photon} = \frac{h c}{E}$

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Class 12th Physics

The rms value of conduction current in a parallel plate capacitor is 6.9 $μ A$ . The capacity of this capacitor, if it is connected to 203 V ac supply with an angular frequency of 600 rad/s, will be:

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Vishal Baghel

Contributor-Level 10

Current in capacitor l = $\frac{V}{X_{C}}$ $\frac{}{_{}}$

I = v * $(ω c)$

$C = \frac{1}{v ω} = \frac{6.9 * 1 0^{- 6}}{230 * 600} = 50 p F$

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