Q9 of 26 Page 1

Define ionization energy.

How would the ionization energy change when electron in hydrogen atom is replaced by a particle of mass 200 times that of the electron but having the same charge?


OR


Calculate the shortest wavelength of the spectral lines emitted in Balmer series. [Given Rydberg constant, R = 107 m-1]

Ionization energy is defined as the minimum amount of energy required to remove an electron from the outermost orbit of a neutral atom in it’s ground state (in other words ionize the atom or put positive charge on it) , so in case of an hydrogen atom it is the energy required to pull out the electron from hydrogen atom


H + Energy -> H + + e-


H is the hydrogen atom, H + is the hydronium ion formed after removal of an electron from a Hydrogen atom


For a hydrogen atom ionization energy of an electron is given by the relation


E = me4/8

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7

A ray PQ incident normally on the refracting face BA is refracted in the prism BAC made of material of refractive index 1.5. Complete the path of ray through the prism. From which face will the ray emerge? Justify your answer.

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Calculate the de-Broglie wavelength of the electron orbitting in the n = 2 state of hydrogen atom.

 10

A battery of emf 12V and internal resistance 2 Ω is connected to a 4 resistor as shown in the figure.


(a) Show that a voltmeter when placed across the cell and across the resistor, in turn, gives the same reading.


(b) To record the voltage and the current in the circuit, why is voltmeter placed in parallel and ammeter in series in the circuit?

11

Define an equipotential surface. Draw equipotential surfaces:

(i) in the case of a single point charge and


(ii) in a constant electric field in Z-direction. Why the equipotential surfaces about a single charge are not equidistant?


(iii) Can electric field exist tangential to an equipotential surface? Give reason.