Physics Ncert Solutions Class 12th

Physics Ncert Solutions Class 12th Waves

Contributor-Level 10

Low pass filter will allow low frequency signal to pass while high pass filter allow high frequency to pass through

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4 months ago

A source of sound S is moving with a velocity of 50 m/s towards a stationary observer. The observer measures the frequency of the source as 1000 Hz. What will be the apparent frequency (in Hz) of the source when it is moving away from the observer after crossing him? (Take speed of sound in air as 350 m/s)

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Physics Ncert Solutions Class 12th Communication Systems

Contributor-Level 10

Kindly consider the following figure

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An antenna is mounted on a 400m tall building. What will be the wavelength of signal that can be radiated effectively by the transmission tower upto a range of 44kg?

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Contributor-Level 10

$λ > h \Rightarrow λ > 400 m$

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Choose the correct waveform that can represent the voltage across R of the following circuit, assuming the diode is ideal one:

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Contributor-Level 10

Diode, in forward biased condition only, will allow current to flow through it.

Pot. different across resistor is

$Δ V = (10 s i n ω t - 3) v o l t$

But in reverse biased condition of diode,

$Δ V = 0$ (across diode)

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4 months ago

In the given circuit find the current through the Zener diode in mA.

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Contributor-Level 10

Potential difference across R?
(R? / (R? +R? ) * V is greater than zenor voltage
⇒ i? = V_z/R? = 20/1000 A = 20 mA
Current through R? , i? = (40-V_z)/R? = 20/500 = 40 mA

Current through zener diode = i? - i? = 20 mA

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Calculate the value of output voltage V₀ (in V) if the Si diode and Ge diode conduct at 0.7V and 0.3V respectively as shown in figure.

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Contributor-Level 10

$I = \frac{12 - 0.3}{5 * 1 0^{3}} = 2.34 m A$

$V_{0} = I R = (2.34 * 1 1^{- 3}) (5 * 1 0^{3}) = 11.7 V$

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4 months ago

Assuming the sun to be a spherical body (e = 1) of radius R at a temperature of T K, evaluate the total radiant power, incident on Earth having radius r₀, at a distance r from the Sun, where r₀ is the radius of the earth and $σ$ is Stefan's constant.

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Contributor-Level 10

\frac{e A_{s u n} σ T^{4}}{4 π r^{2}} * A_{p r o j E a r t h}

\frac{4 π R^{2}}{4 π r^{2}} σ T^{4} π r_{0}^{2}

π \frac{R^{2}}{r^{2}} r_{0}^{2} σ T^{4}

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4 months ago

At t < 0, the capacitor is charged and the switch is opened. At t = 0 the switch is closed. The shortest time T at which the charge on the capacitor will be zero is given by:

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Contributor-Level 10

The time period of LC oscillations,

$T = 2 π \sqrt[]{L C}$

The time at which charge on the capacitor will be zero is $\frac{T}{4} .$

So t $= \frac{π}{2} \sqrt[]{L C}$

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4 months ago

In the figure, there is a conducting wire having current i and which has a shape of closed half ellipse $[\frac{x^{2}}{a^{2}} + \frac{y^{2}}{b^{2}} = 1]$ is kept in a uniform magnetic field B as shown. The magnitude of magnetic dipole moment of loop and torque acting on it are-

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Area of ellipse = $π a b$

Magnetic dipole moment = $\frac{π a b i}{2}$

Torque $\vec{τ} = \vec{M} * \vec{B}$

$τ = M B s i n θ$

$? \vec{M} | | \vec{B}$ $τ = 0$

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4 months ago

Which of the following transitions of He⁺ ion will give rise to spectral line which has same wavelength as some spectral line in hydrogen atom?

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