Science (English Medium) Class 12 - CBSE Question Bank Solutions for Physics

Write any two factors which justify the need for modulating a signal ?

Draw a diagram showing an amplitude modulated wave by superposing a modulating signal over a sinusoidal carrier wave.

A proton and an electron have same kinetic. Which one has greater de-Broglie wavelength and why?

The ground state energy of hydrogen atom is −13.6 eV. If and electron make a transition from the energy level −0.85 eV to −3.4 eV, calculate spectrum does his wavelength belong?

Explain briefly the principle on which a transistor-amplifier works as an oscillator. Draw the necessary circuit diagram and explain its working ?

A proton and an electron have same velocity. Which one has greater de-Broglie wavelength and why?

The ground state energy of hydrogen atom is −13.6 eV. If an electron make a transition from an energy level −0.85 eV to −1.51 eV, calculate the wavelength of the spectral line emitted. To which series of hydrogen spectrum does this wavelength belong?

Show on a graph the variation of the de Broglie wavelength (λ) associated with an electron, with the square root of accelerating potential (V) ?

When monochromatic light is incident on a surface separating two media, why does the refracted light have the same frequency as that of the incident light?

Obtain the conditions for the bright and dark fringes in diffraction pattern due to a single narrow slit illuminated by a monochromatic source.

Explain clearly why the secondary maxima go on becoming weaker with increasing.

Using de Broglie’s hypothesis, explain with the help of a suitable diagram, Bohr’s second postulate of quantization of energy levels in a hydrogen atom.

Write briefly any two factors which demonstrate the need for modulating a signal. Draw a suitable diagram to show amplitude modulation using a sinusoidal signal as the modulating signal.

 State Huygen’s principle. Using this principle explain how a diffraction pattern is obtained on a screen due to a narrow slit on which a narrow beam coming from a `=> n = (vlamda)/(vlamda_omega)`monochromatic source of light is incident normally.

If a monochromatic source of light is replaced by white light, what change would you observe in the diffraction pattern?

An electron is accelerated through a potential difference of 64 volts. What is the de-Broglie wavelength associated with it? To which part of the electromagnetic spectrum does this value of wavelength correspond?

An electron, an alpha particle and a proton have the same kinetic energy.

Which one of these particles has the largest de-Broglie wavelength? 

Which of the following sources provides the best monochromatic light?

The following figure shows three equidistant slits being illuminated by a monochromatic parallel beam of light. Let \[B P_0  - A P_0  = \lambda/3\text{ and }D >  > \lambda.\] (a) Show that in this case \[d = \sqrt{2\lambda D/3}.\] (b) Show that the intensity at P₀ is three times the intensity due to any of the three slits individually.

Consider the situation shown in the figure. The two slits S₁ and S₂ placed symmetrically around the central line are illuminated by a monochromatic light of wavelength λ. The separation between the slits is d. The light transmitted by the slits falls on a screen ∑₁placed at a distance D from the slits. The slit S₃ is at the central line and the slit S₄ is at a distance z from S₃. Another screen ∑₂ is placed a further distance D away from ∑_1.Find the ratio of the maximum to minimum intensity observed on ∑₂ if z is equal to

(a) \[z = \frac{\lambda D}{2d}\]

(b) \[\frac{\lambda D}{d}\]

(c) \[\frac{\lambda D}{4d}\]

"Monochromatic light should be used to produce pure spectrum". Comment on this statement.