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11 months ago

Physics Units and Measurement

In a vernier calipers, each cm on the main scale is divided into 20 equal parts. If tenth vernier scale division coincides with nineth main scale division. Then the value of vernier constant will be__________* 10^-²mm.

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Raj Pandey

Contributor-Level 9

Let 'x' he the value of one division of main scale

$x = \frac{1}{20} c m = 0.05 c m$

Let y be value of one division on venire scale given

10 y = 9 x

$y = \frac{9 x}{10}$

Least count = $x - \frac{9 x}{10} = \frac{x}{10} = \frac{0.05}{10}$

= 0.005 cm

= 5 * 10^-2 mm

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11 months ago

Physics Physics Ray Optics and Optical Instruments

A light ray is incident, at an incident angle q₁, on the system of two plane mirrors M₁ and M₂ having an inclination angle 75° between them (as shown in figure). After reflecting from mirror M₁ it gets reflected back by the mirror M₂ with an angle of reflection 30°. The total deviation of the ray will be ___________ degree.

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Raj Pandey

Contributor-Level 9

$δ_{t o t a l} = 360 ° - 2 θ$

= 360 – 2 * 75° = 210°

Total deviation = $δ = 150 °$

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11 months ago

Physics Electromagnetic Induction

A $10 Ω$ 20 mH coil carrying constant current is connected to a battery of 20 V through a switch. Now after switch is opened current becomes zero in 100 $μ s .$ The average e.m.f. induced in the coil is__________V.

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Raj Pandey

Contributor-Level 9

Decay of current in Inductor is given by,

$i = i_{0} e^{- t / τ} [W h e r e τ = \frac{L}{R}; i_{0} = \frac{v}{R} = \frac{20}{10} = 2]$

At t = 100 $μ s$

i = 0

i.e. i = i₀ $e^{- 100 / τ} = 0$ -(1)

e.m.f induced

$e = \frac{- L d i}{d t} = - L \frac{d}{d t} [i_{0} e^{- t / τ}]$

...more

Decay of current in Inductor is given by,

$i = i_{0} e^{- t / τ} [W h e r e τ = \frac{L}{R}; i_{0} = \frac{v}{R} = \frac{20}{10} = 2]$

At t = 100 $μ s$

i = 0

i.e. i = i₀ $e^{- 100 / τ} = 0$ -(1)

e.m.f induced

$e = \frac{- L d i}{d t} = - L \frac{d}{d t} [i_{0} e^{- t / τ}]$

= $= - L i_{0} \frac{- 1}{2} e^{- t / τ}$

$e = \frac{L i_{0}}{τ} e^{- t / τ}$

$e_{a v g} = \frac{\int_{0}^{200 μ s} e d t}{\int_{0}^{200 μ s} d t} = \frac{\int_{0}^{200 μ s} \frac{L i_{0}}{τ} e^{- t / τ} d t}{\int_{0}^{200 μ s} d t}$

$= \frac{L i_{0}}{200 * 1 0^{- 6} s e c} = \frac{20 * 1 0^{- 3} * 2}{200 * 1 0^{- 6}} = 400$

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11 months ago

Physics Physics Mechanical Properties of Solids

The elongation of a wire on the surface of the earth is 10^-⁴m. The same wire of same dimensions is elongated by 6 * 10^-⁵ m on another planet. The acceleration due to gravity on the planet will be__________ms^-². (Take acceleration due to gravity on the surface of earth = 10 ms^-²)

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Raj Pandey

Contributor-Level 9

$Δ L$ (change in length) $= \frac{F l}{A E} = \frac{m g l}{A E}$

$Δ l \propto g$

$\frac{Δ l_{1}}{g_{1}} = \frac{Δ l_{2}}{g_{2}} \Rightarrow \frac{1 0^{- 4}}{10} = \frac{6 * 1 0^{- 5}}{g_{1}}$

$g_{1} = \frac{6 * 1 0^{- 4}}{1 0^{- 4}} =$ 6 m/sec²

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11 months ago

Physics Physics Mechanical Properties of Solids

The elastic behavior of material for linear stress and linear strain, is shown in the figure. The energy density for a linear strain of 5 * 10^-⁴ is __________KJ/m³. Assume that material is elastic upto the linear strain of 5 * 10^-⁴.

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Raj Pandey

Contributor-Level 9

$Y = \frac{σ}{\in} = \frac{20}{1 0^{- 10}},$ Y → young's modules of elasticity.

Stress $(σ)$ at strain $(\in)$ 5 * 10^-4

$σ = \in Y$

$= 5 * 1 0^{- 4} * 20 * 1 0^{10}$

= $1 0^{2} * 1 0^{6}$

= 10⁸

$U_{d} (E n e r g y d e n s i t y) = \frac{1}{2} σ \in$

$= \frac{1}{2} * 1 0^{8} * 5 * 1 0^{- 4}$

$\begin{array}{l} = 2.5 * 1 0^{4} \\ = 25 * 1 0^{3} = 25 k J / m^{3} \end{array}$

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11 months ago

Physics Physics Motion in Straight Line

A ball of mass 0.5 kg is dropped from the height of 10m. The height, at which the magnitude of velocity becomes equal to the magnitude of acceleration due to gravity, is __________m.

[Use g = 10m/s²]

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Raj Pandey

Contributor-Level 9

Let 'h' be the height at which velocity becomes equal to magnitude of Acceleration

v = g = 10

v = u + at

10 = 0 + 10t

t = 1 sec

$h = u t + \frac{1}{2} a t^{2}$

$= 0 * 1 + \frac{1}{2} * 10 * 1 * 1$

= 5m

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11 months ago

Physics Class 11th

A fighter jet is flying horizontally at a certain with a speed of 200ms^-1. When it passes directly overhead ad anti-aircraft gun, a bullet is fired from the gun, at an angle (θ)with the horizontal, to hit the jet. If the bullet speed is 400m/s, the value of (θ)will be _____________.

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Raj Pandey

Contributor-Level 9

B → fighter jet

A → anti-Air craft gun

Draw velocity diagram of A w.r.t. B

If A hits B

Then Relative velocity perpendicular to the line joining A to B will be zero.

That means 400 cos q = 200

&nbs

...more

B → fighter jet

A → anti-Air craft gun

Draw velocity diagram of A w.r.t. B

If A hits B

Then Relative velocity perpendicular to the line joining A to B will be zero.

That means 400 cos q = 200

$\begin{array}{l} c o s θ = \frac{1}{2} \\ θ = 60 ° \end{array}$

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11 months ago

Physics Physics Ncert Solutions Class 12th

Choose the correct statement for amplitude modulation :

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Raj Pandey

Contributor-Level 9

In amplitude modulation, the amplitude of the career signal is varied in according with the modulating signal.

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11 months ago

Physics Physics Semiconductor Devices

The I-V characteristics of p-n junction diode in forward bias is shown in the figure. The ration of dynamic resistance, corresponding to forward bias voltage of 2 V and 4 V respectively, is