Question 3

What is the shortest wavelength present in the Paschen series of spectral lines?

Answer

Rydberg’s formula is given as: *hc/λ* = 21.76 x 10^{-19} [1/(n_{1})^{2} - 1/(n_{2})^{2}]

Where, h = Planck’s constant = 6.6 × 10 ^{−34} Js

c = Speed of light = 3 × 10 ^{8} m/s

(n _{1} and n _{2} are integers)

The shortest wavelength present in the Paschen series of the spectral lines is given for values n _{1} = 3 and n _{2} = ∞.

hc/λ = 21.76 x 10^{-19} [1/(3)^{2} - 1/(∞)^{2}]

∴ λ = 6.6 x 10^{-34} x 3 x 10^{8} x 9 / 21.76 x 10^{-19} = 8.189x10^{-7} m = 818.9 nm

*Hence, the shortest wavelength present is 818.9 nm.*

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- Q:-
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(b) If a negative test charge of magnitude 1.5 × 10

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A uniformly charged conducting sphere of 2.4 m diameter has a surface charge density of 80.0 μC/m

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(b) What is the total electric flux leaving the surface of the sphere?

- Q:-
Two charges 5 x 10

^{-8}C and -3 x 10^{-8}C are located 16 cm apart. At what point(s) on the line joining the two charges is the electric potential zero? Take the potential at infinity to be zero. - Q:- A 100 Ω resistor is connected to a 220 V, 50 Hz ac supply.

(a) What is the rms value of current in the circuit?

(b) What is the net power consumed over a full cycle?

- Q:-
Two charges 5 x 10

^{-8}C and -3 x 10^{-8}C are located 16 cm apart. At what point(s) on the line joining the two charges is the electric potential zero? Take the potential at infinity to be zero. - Q:- ">

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- Q:-
A polythene piece rubbed with wool is found to have a negative charge of 3 × 10

^{−7}C.(a) Estimate the number of electrons transferred (from which to which?)

(b) Is there a transfer of mass from wool to polythene?

- Q:-
A point charge causes an electric flux of −1.0 × 10

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- Q:-
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- Q:- ">
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- Q:-
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^{3}N/C and points radially inward, what is the net charge on the sphere? - Q:-
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- Q:-
that the capacitance of a spherical capacitor is given by

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that the capacitance of a spherical capacitor is given by

where

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- NCERT Chapter

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