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# Multiple choice questions on optics LCR circuits etc.

1. In a series LCR circuit at resonance, decide which of the following statements are true:

a) The current leads the voltage across the generator
b) The current is in phase with the Voltage
c) The impedance is at a minimum
d) The current is at a minimum
e) The resonance frequency is determined by the inductance, the capacitance, and the resistance.

2. In an unidentified ionized atom, only one electron moves about the nucleus. The radius of the n=3 Bohr orbit is 2. 38 x 10^-10m. What is the energy(in electron Volts) of the n=7 orbit for this atom?

a) -1.11 eV
b) -1.51 eV
c) -3.40 eV
d) -6.04 eV
e) -13.6 eV

3. A film of oil lies on glass(n of glass =1.52). The refractive index of the oil is smaller than that of the glass. The film has the minimum non-zero constructive interference when viewed in red light (Wavelength = 66 Dnm in a vacuum). Assuming that a visible spectrum extends from 380 to 750 nm, what are the visible wavelength(s) in vaccum for which the film will appear dark due to destructive interference?

a) 396 nm
b) 495 nm
c) 440 nm
d) 550 nm
e) 742 nm

4. Radiation with a wavelength of 280 nm shines on a metal surface and ejects electrons that have a maximum speed of 3.48 X 10^5 m/s. Which one of the following metals is it(the values in parenthesis are the work functions)?

a) Potassium ( 2.24 eV)
b) Calcium ( 2.71 eV)
c) Uranium ( 3.63 eV)
d) Aluminum (4.08 eV)
e) Gold(4.82 eV)

#### Solution Summary

There are multiple choice questions related to LCR circuits, Bohr model, interference through thin films and photo electric effect.

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