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Physics Atoms

If an electron is moving in the nth orbit of the hydrogen atom, then its velocity (v_n) for the nth orbit is given as :

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Vishal Baghel

Contributor-Level 10

Velocity of an electron in the nth orbit:

v ∝ 1/n

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Physics Class 11th

Two identical metal of thermal conductivities K₁ and K₂ respectively are connected in series. The effective thermal conductivity of the combination is:

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Vishal Baghel

Contributor-Level 10

R_eq = R? + R?

L_total / (K_eq * A) = L? / (K? A) + L? / (K? A)
Assuming L? = L? = l, L_total = 2l

2l / (K_eq * A) = l/ (K? A) + l/ (K? A)

2/K_eq = 1/K? + 1/K? = (K? + K? )/ (K? )

K_eq = 2K? K? / (K? + K? )

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Physics Thermodynamics

Two ideal polyatomic gases at temperatures T₁ and T₂ are mixed so that there is no loss of energy. If F₁ and F₂, m₁ and m₂, n₁ and n₂ be the degrees of freedom, masses, number of molecules of the first and second gas respectively, the temperature of mixture of these two gases is:

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Vishal Baghel

Contributor-Level 10

U = U? + U? = (n? /N_A) (F? R/2)T? + (n? /N_A) (F? R/2)T?

For the mixture: U = (n? +n? )/N_A * (FR/2)T

F = (n? F? + n? F? ) / (n? + n? )

Equating the expressions for U and solving for T gives:
T = (n? F? T? + n? F? T? ) / (n? F? + n? F? )

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Physics Class 12th

An AC current is given by I = I₁sinωt + I₂cosωt. A hot wire ammeter will give a reading:

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Vishal Baghel

Contributor-Level 10

I = I? sin (ωt) + I? cos (ωt)

This can be written as I = I? sin (ωt + φ), where I? = √ (I? ² + I? ²)

A hot wire ammeter reads the rms value of the current.

I_rms = I? /√2 = √ (I? ² + I? ²)/√2

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Physics Oscillations

For what value of displacement the kinetic energy and potential energy of a simple harmonic oscillation become equal?

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Vishal Baghel

Contributor-Level 10

K = U

½ mω² (A² - x²) = ½ mω²x²

A² - x² = x²

A² = 2x²

x = ± A/√2

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Physics Class 11th

When two soap bubbles of radii a and b (b > a) coalesce, the radius of curvature of common surface is:

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Vishal Baghel

Contributor-Level 10

P? - P? = 4T/a

P? - P? = 4T/b

P? - P? = 4T (1/a - 1/b)

Also, P? - P? = 4T/r

4T/r = 4T (1/a - 1/b)

1/r = (b-a)/ab

r = ab / (b-a)

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Physics Thermodynamics

A Carnot's engine working between 400 K and 800 K has a work output of 1200J per cycle. The amount of heat energy supplied to the engine from the source in each cycle is:

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Vishal Baghel

Contributor-Level 10

η = 1 - T_C / T_H

η = 1 - 400/800 = 1 - ½ = ½

η = W/Q_H ⇒ ½ = W/Q_H ⇒ Q_H = 2W = 2 * 1200 = 2400 J

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10 months ago

Physics Physics Moving Charges and Magnetism

A solenoid of 1000 turns per meter has a core with relative permeability 500. Insulated windings of the solenoid carry an electric current of 5 A. The magnetic flux density produced by the solenoid is: (permeability of free space = 4π*10^-7H/m)

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