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11 months ago

Class 12th Electromagnetic Waves

The electric field in an electromagnetic wave is given by E = 56.5 sin $ω (t - x / c) N C^{- 1} .$ Find the intensity of the wave if it is propagating along x-axis in the free space.

(Given $\in_{0} = 8.85 * 1 0^{- 12} C^{2} N^{- 1} m^{- 2}$ )

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Vishal Baghel

Contributor-Level 10

$E = 56.5 s i n (w (\frac{t - x}{c})) N / c$

$E_{0} = 56.5$

$ε_{0} = 8.85 * 1 0^{- 12}$

C = 3 * 108

l = $\frac{1}{2} ε_{0} E_{0}^{2} C$

$= \frac{1}{2} * 8.85 * 1 0^{- 12} * {(56.5)}^{2} * 3 * 1 0^{8}$

$= 42377.11 * 1 0^{- 4}$

$l = 4.24 w m^{- 2}$

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11 months ago

Class 12th Physics

If wattles current flows in the AC circuit, then the circuit is:

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Vishal Baghel

Contributor-Level 10

Purely inductive circuit

$θ = \frac{π}{2}$

$c o s \frac{π}{2} = 0$

Average power = 0

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11 months ago

Class 12th Physics Moving Charges and Magnetism

A long straight wire with a circular cross-section having radius R, is carrying a steady current I: The current I is uniformly distributed across this cross-section. Then the variation of magnetic field due to current I with distance r(r < R) from its centre will be:

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Vishal Baghel

Contributor-Level 10

for $π R^{2} A r e a \to' l'$ $^{}$ current

1 unit Area $\frac{l}{π R^{2}}$ $\frac{}{^{}}$

$π r^{2} \to \frac{l}{π R^{2}} * π r^{2}$

$i = \frac{l r^{2}}{R^{2}}$

Now, consider Amperian loop of radius small 'r' ln Amperian loop magnetic field will be tangential to the amperian loop.

$? \vec{B} . d \vec{i} = μ_{0} l_{e n c l o s e d}$ (Ampere circuital law)

$B = \frac{μ_{0}}{2 π} \frac{l}{R^{2}} r$

$B \propto r$

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11 months ago

Class 12th Physics

In the figure, a very large plane sheet of positive charge is shown. P1 and P2 are two points at distance $l a n d 2 l$ from the charge distribution. If $σ$ is the surface charge density, then the magnitude of electric fields E₁ and E₂ at P₁ and P₂ respectively are:

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Vishal Baghel

Contributor-Level 10

(Independent of distance)

$E_{1} = E_{2} = \frac{σ}{2 \in_{0}}$

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11 months ago

Class 12th Physics

In an experiment of CE configuration of n-p-n transistor, the transfer characteristics are observed as given in figure.

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alok kumar singh

Contributor-Level 10

Voltage gain = $\frac{I_{C} R_{0}}{I_{B} R_{i}}$

R₀ ->Output Resistance

R_i ->Input Resistance

I_C ->Collector current

I_{B ->}Base current

Voltage gain = $\frac{I_{C}}{I_{B}} \frac{R_{0}}{R_{i}} = \frac{(5 * 1 0^{- 3})}{(100 * 1 0^{- 6})} * \frac{60}{200} = 15$

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11 months ago

Class 12th Chemistry

A compound 'X' is a weak acid and it exhibits colour change at pH close to the equivalence point during neutralization of NaOH with CH₃COOH. Compound 'X' exists in ionized form in basic medium. The compound 'X' is

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Payal Gupta

Contributor-Level 10

Phenolphthalein is the indicator of weak acid which produces pink colour in basic medium.

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11 months ago

Class 12th Chemistry

When ethanol is heated with conc. H₂SO₄, a gas is produced. The compound formed, when this gas is treated with cold dilute aqueous solution of Baeyer's reagent, is

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