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Physics Physics Electromagnetic Waves

An electromagnetic wave of frequency 5 GHz, is travelling in a medium whose relative electric permittivity and relative magnetic permeability both are 2. Its velocity in the this medium is_____* 10⁷ m/s.

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alok kumar singh

Contributor-Level 10

$v = \frac{1}{\sqrt[]{ε μ}} = \frac{1}{\sqrt[]{2 ε_{0} . 2 μ_{0}}} = \frac{1}{2 \sqrt[]{ε_{0} μ_{0}}} = \frac{c}{2} = 15 * 1 0^{7} m / s .$

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2 months ago

Physics Class 12th

A common transistor ratio set requires 12V (D.C) for its operation. The D.C source is constructed by using a transformer and a rectifier circuit, which are operated at 220V (A.C) on standard domestic A.C, supply. The number of turns of secondary coil are 24, then the number of turns of primary are___________.

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alok kumar singh

Contributor-Level 10

$\frac{N_{p}}{N_{s}} = \frac{V_{p}}{V_{s}} \Rightarrow N_{p} = \frac{V_{p}}{V_{s}} * N_{s} = \frac{220}{12} * 24 = 440$

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2 months ago

Physics Physics Wave Optics

An unpolarized light beam is incident on the polarizes of a polarization experiment and the intensity of light beam emerging from the analyzer is measured as 100 Lumens. Now, if the analyzer is rotated around the horizontal axis (direction of light) by 30° in clockwise direction, the intensity of emerging light will be________ Lumens.

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alok kumar singh

Contributor-Level 10

$l = l_{0} c o s^{2} θ = 100 * c o s^{2} (30 °) = 75 L u m e n s$

Note : As the incident light is unpolarized, intensity of emerging light does not depend on the polarization axis of polarizer.

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2 months ago

Physics Work, Energy and Power

An inclined plane in bent in such a way that the vertical cross-section is given by y $= \frac{x^{2}}{4}$ where y is in vertical and x in horizontal direction. If the upper surface of this curved plane is rough with coefficient of friction $μ$ = 0.5, the maximum height in cm at with a stationary block with not skip downward is ____________cm.

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alok kumar singh

Contributor-Level 10

If the block does not slide,

mg sin $θ \leq μ m g c o s θ$

$\Rightarrow t a n θ \leq μ \Rightarrow \frac{d y}{d x} \leq μ \Rightarrow \frac{x}{2} \leq 0.5 \Rightarrow x \leq 1 m .$

Thus, $y \leq \frac{1^{2}}{4} = 0.25 m = 25 c m .$

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2 months ago

Physics Class 11th

A ball with a speed of 9m/s collides with another identical ball at rest. After the collision the direction of each ball makes an angle 30° with the original direction. The ratio of velocities of the balls after collision is x : y, where x is_________.

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alok kumar singh

Contributor-Level 10

Using conversation of momentum in direction perpendicular to the original direction of motion,

mv₁ sin 30° = mv₂ sin 30°

$\Rightarrow \frac{v_{1}}{v_{2}} = 1$

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Physics Class 12th

A resonance circuit having inductance and resistance 2 * 10^-4 H and 6.28 $Ω$ respectively oscillates at 10 MHz frequency. The value of quality factor of this resonator is__________.

[p = 3.14]

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alok kumar singh

Contributor-Level 10

Quality factor = $\frac{ω L}{R} = \frac{2 * 3.14 * 10 * 1 0^{6} * 2 * 1 0^{- 4}}{6.28} = 2000$

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2 months ago

Physics Class 11th

The coefficient of static friction between a wooden block of mass 0.5kg and a vertical rough wall is 0.2. The magnitude of horizontal force that should be applied on the block to keep it adhere to the wall be__________ N.

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alok kumar singh

Contributor-Level 10

f = W = 0.5 * 10 = 5 N

N = F

For block not to slide,

$f \leq μ N$

$\begin{array}{l} \Rightarrow 5 \leq 0.2 F \\ \Rightarrow F \geq 25 N \end{array}$

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2 months ago

Physics Physics Mechanical Properties of Fluids

A hydraulic press can lift 100kg when a mass 'm' is place on the smaller piston. It can lift_______ kg when the diameter of the large piston in increases by 4 times and that of the smaller piston is decreased by 4 times keeping the same mass 'm' on the smaller piston.

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