CBSE Class 12 · Physics

Optics and Modern Physics

20 practice questions, each with the answer and an explanation.

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A ray of light travels from an optically denser medium of refractive index $μ = 2$ into air. What is the critical angle of incidence for total internal reflection?
An equilateral glass prism ( $A = 6 0^{\circ}$ ) produces a minimum angle of deviation of $D_{m} = 6 0^{\circ}$ . What is the refractive index of the prism material?
In a Young's double slit experiment, the slit separation is halved and the distance between the slits and the screen is doubled. By what factor does the interference fringe width change?
When unpolarized light is incident on a transparent medium of refractive index $μ = 3$ at Brewster's angle, what is the angle of refraction?
The work function of a photosensitive metal is $Φ_{0} = 3.3 eV$ . What is the threshold frequency of incident radiation required to liberate photoelectrons? (…
An electron of mass $m$ and charge $e$ is accelerated from rest through a potential difference $V$ . Which expression gives its de Broglie wavelength?
In a photoelectric experiment, when radiation of frequency $ν$ is incident on a cathode, photoelectrons are emitted with maximum kinetic energy $K_{m a x}$ . If the incident intensity is doubled at th…
In the Bohr model of the hydrogen atom, how does the radius $r_{n}$ of the $n$ -th stationary orbit scale with the principal quantum number $n$ ?
To which region of the electromagnetic spectrum do the spectral lines of the Lyman series of atomic hydrogen belong?
How does the nuclear matter density $ρ$ of an atomic nucleus of mass number $A$ depend on $A$ ?
The decay constant of a radioactive isotope is $λ$ . What is the expression for its half-life $T_{1/2}$ ?
What is the typical magnitude of the forbidden energy band gap ( $E_{g}$ ) for a semiconductor such as Silicon at room temperature?
What happens to the width of the depletion layer and the potential barrier when a p-n junction diode is forward biased?
An alternating supply of frequency $50 Hz$ is fed into a full-wave bridge rectifier. What is the ripple frequency of the output direct voltage?
In a compound microscope, the focal length of the objective lens is $f_{o} = 1 cm$ and that of the eyepiece is $f_{e} = 5 cm$ . An object is placed $1.1 cm$ in front of the objectiv…
An astronomical telescope in normal adjustment has an objective of focal length $100 cm$ and an eyepiece of focal length $5 cm$ . What are its magnifying power and the separation betwee…
How much work is done in moving an electric charge of $5 μ C$ between any two points situated on the same equipotential surface?
A galvanometer of resistance $G = 50 Ω$ gives full-scale deflection for current $I_{g} = 10 mA$ . What shunt resistance $S$ is required to convert it into an ammeter of range $0$ to…
A planar circular coil of $N = 100$ turns and radius $r = 0.1 m$ carries current $I = 2 A$ . If placed in a uniform magnetic field $B = 0.5 T$ with its plane parallel to the fie…
The mass defect in the formation of a helium nucleus ( $_{2}^{4} He$ ) is $Δ m = 0.0304 u$ . What is the total binding energy of the helium nucleus? (…

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Optics and Modern Physics

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