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5 months ago

Class 12th Physics Atoms

In the hydrogen spectrum, $λ$ be the wavelength of first transition line of Lyman series. The wavelength difference will be $" a λ "$ between the wavelength of 3^rd transition line of Paschen series and that 2^ndtransition line B Balmer series where a = __________.

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Payal Gupta

Contributor-Level 10

For first line of Lyman

$\frac{1}{λ} = R (1 - \frac{1}{4}) = R \frac{3}{4}$

$λ = \frac{4}{3 R}$

3rd line (Paschen)

$\frac{1}{λ_{3}} = R (\frac{1}{3^{2}} - \frac{1}{6^{2}}) = \frac{R}{9} * \frac{3}{4}$

2nd line (B almer)

${\frac{1}{λ}}_{2} = R (\frac{1}{2^{2}} - \frac{1}{4^{2}}) = \frac{R}{4} * \frac{3}{4}$

$a (\frac{4}{3 R}) = \frac{20}{3 R} \Rightarrow a = 5$

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5 months ago

Class 12th Physics Ray Optics and Optical Instruments

The graph between $\frac{1}{u} a n d \frac{1}{v}$ for a thin convex lens in order to determine its focal length is plotted as shown in the figure. The refractive index of lens is 1.5 and its both the surfaces have same radius of curvature R. The value of R will be _________cm. (where u = object distance, v = image distance)

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Payal Gupta

Contributor-Level 10

for point B, $\frac{1}{u} = - 0.10 c m^{- 1}, \frac{1}{v} = 0$

Thus u = 10 cm, v = $\infty$

i.e., f = 10 cm

$\frac{1}{10} = (1.5 - 1) (\frac{2}{R}) \Rightarrow \frac{1}{R} = \frac{1}{10}$

R = 10 cm

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Class 12th Physics Alternating Current

The effective current I in the given circuit at very high frequencies will be _________A.

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Payal Gupta

Contributor-Level 10

At very high frequencies

$X_{C} = \frac{1}{ω C} \to 0$

$X_{L} = ω L \to \infty$

Thus equivalent circuit

$Z = 1 + 2 + 2 = 5 Ω$

$l = \frac{220}{5} = 44 A$

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5 months ago

Class 12th Physics

Resistances are connected in a meter bridge circuit as shown in the figure. The balancing length $l_{2}$ is 40cm. Now as unknown resistance x is connected in series with P and new balancing length is found to be 80cm measured from the same end. Then the value of x will be _________ $Ω$ .

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Payal Gupta

Contributor-Level 10

Initially, $\frac{P}{Q} = \frac{40}{60} = \frac{2}{3}$ - (1)

Finally, $\frac{P + x}{Q} = \frac{80}{20} = \frac{4}{1}$

(2) (1)

$\frac{P + x}{P} = \frac{4 * 3}{2} = 6$

$\Rightarrow 1 + \frac{x}{P} = 6$

$\frac{x}{P} = 5$

x = 5 P = 5 * 4 = 20 $Ω$

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Class 12th Physics Electrostatic Potential and Capacitance

A composite parallel plate capacitor is made up to two different dielectric materials with different thickness (t₁ and t₂) as shown in figure. The two different dielectric materials are separated by a conducting foil F. The voltage of the conducing foil is ___________V.

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Payal Gupta

Contributor-Level 10

Capacitance of each capacitor

$C_{1} = \frac{A 3 ε_{0}}{\frac{1}{2}} = 6 A ε_{0}$

$C_{2} = A 4 ε_{0} = 4 A ε_{0}$

Equivalent capacitance

$Δ v_{2} = \frac{240 A ε_{0}}{4 A ε_{0}} = 60 v$

$v_{f o i l} = 60 v$

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5 months ago

Class 12th Physics Wave Optics

When a car is approaching the observer, the frequency of horn is 100Hz. After passing the observer, it is 50 Hz. If the observer moves with the car, the frequency will be $\frac{x}{3}$ Ha where x = _________.

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Payal Gupta

Contributor-Level 10

$f_{1} = 100 = f o (\frac{C}{C - V_{S}})$

C = Speed of sound

Vs = Speed of source

f2 = 50 = fo = $(\frac{C}{C + V_{s}})$

$\frac{f_{1}}{f_{2}} = 2 = \frac{C + V_{S}}{C - V_{S}}$

$f o = \frac{200}{3} = \frac{x}{3}$

x = 200

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Class 12th Techno International New Town

Can I get admission in Techno International New Town for BBA with 60% in Class 12th?

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Sejal Baveja

Contributor-Level 10

Yes, candidates can take admission in BBA course at Techno International New Town with 60% in Class 12. The college has not specified the minimum required aggregate for admission, however since 60% is a decent score, the college can grant them admission. They must appear for the MAKAUT CET exam to get selected for BBA course at Techno International New Town and achieve the required aggregate in the same.

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Class 12th Physics

The total charge on the system of capacitors $C_{1} = 1 μ F, C_{2} = 2 μ F, C_{3} = 4 μ F a n d C_{4} = 3 μ F$ connected in parallel is:

(Assume a battery of 20V is connected to the combination)

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Payal Gupta

Contributor-Level 10

$C_{e q} = C_{1} + C_{2} + C_{3} + C_{4}$

= 1 + 2 + 4 + 3

$= 10 μ F$

Q = C_eq v

= (10 * 20) $μ C$

Q = 200 $μ C$

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5 months ago

Class 12th Physics

The current I in the above given circuit will be

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Payal Gupta

Contributor-Level 10

$R = \frac{8}{2} Ω = 4 Ω$ (wheat stone bridge)

$I = \frac{V}{R} = \frac{40}{4} = 10 A$

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5 months ago

Class 12th Physics

B_X and B_Y are the magnetic fields at the centre of two coils X and Y respectively each carrying equal current. If coil X has 200 turns and 20 cm radius and coil Y has 400 turns and 20 cm radius, the ratio of B_X and B_Y is

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Payal Gupta

Contributor-Level 10

$B = N \frac{μ_{0} l}{2 μ}$

$B α \frac{N}{μ}$

$\frac{β_{x}}{β_{y}} = \frac{N_{x}}{r_{x}} * \frac{r_{y}}{N_{y}}$

$\frac{B_{x}}{B_{y}} = \frac{200}{20} * \frac{20}{400} = \frac{1}{2}$

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