List of top Physics Questions

In Bohr's model of hydrogen atom, which of the following is an integral multiple of \(\dfrac{h}{2\pi}\) ?
If \(r_1\) and \(r_2\) are the radii of the atomic nuclei of mass number 4 and 32, respectively, then the ratio \(\left(\dfrac{r_1}{r_2}\right)\) is
Match the LIST-I with LIST-II (In the context of Young's double slit experiment)
LIST-ILIST-II
A. The width of one slit is slightly increased.I. The fringe width increases.
B. One slit is closed.II. Interference pattern becomes less sharp.
C. The width of the source slit is increased.III. Maximum intensity increases
D. Light of smaller frequency is used.IV. Interference pattern disappears
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If the two slits in a Young's double slit experiment have their widths in the ratio 4:1, then the ratio of intensities at maxima and minima in the interference pattern will be
In a Young's double slit experiment, the intensity at the center of the screen is I. If one of the slits is closed, the intensity at the center of the screen now will be:
A ray of light of frequency \(5 \times 10^{14}\) Hz is passed through a liquid. The wavelength of light measured inside the liquid is found to be \(450 \times 10^{-9}\) m. The refractive index of the liquid is
Arrange the following photosensitive metals (work function given in brackets) according to their threshold wavelengths in decreasing order of their values.
A. K (\(\Phi\) = 2.3 eV)
B. Na (\(\Phi\) = 2.75 eV)
C. Cs (\(\Phi\) = 2.14 eV)
D. Ca (\(\Phi\) = 3.2 eV)

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A concave mirror forms a real image of an object kept at a distance of 9 cm from it. If the object is taken away further from the mirror by 6 cm, the image size is reduced to \((1/4)^{th}\) of its previous size. The focal length of the mirror is:
A real image is formed by a convex lens on the screen. If half of the lens is covered by an opaque object, then
Identify the correct statements among the following.
A. All electromagnetic waves, irrespective of their frequencies, travel at the same speed through vacuum.
B. A capacitor is fully charged by a d.c. source. When it is fully charged, the displacement current is zero.
C. Ultraviolet radiation can be used for viewing objects through haze and fog.
D. A moving charge in a circular orbit cannot produce electromagnetic waves.
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A radiation of energy \(E\) falls normally on a perfectly reflecting surface. The momentum transferred to the surface is
The intensity of a laser beam is \(2.5 \times 10^{14}\ \text{W/m}^2\). The amplitude of the magnetic field in the beam is
(Given, \(\epsilon_0 = 8.85 \times 10^{-12}\ \text{C}^2\text{N}^{-1}\text{m}^{-2}\))
Arrange the following substances/media in the increasing order of their refractive indices.
A. Crown glass
B. Water
C. Diamond
D. CO2
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Arrange the following electromagnetic waves in the ascending order of their energies.
A. X-rays
B. UV-rays
C. Infrared rays
D. Microwaves
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A pure inductor of 0.25 H is connected to a source of 220 V. If the frequency of the source is 50 Hz, then the rms current in the circuit will be.
The conduction current is same as displacement current in a circuit when the source is
An a.c. voltage is applied to a pure inductor. The current in the inductor would be
A coil with an average diameter of 0.02 m is placed with its plane perpendicular to a magnetic field of 6000 T. The induced emf in the coil is 11 V, when the magnetic field is changed to 1000 T in 4 s. The number of turns in the coil is
Identify the correct statement(s) among the following.
A. In a d.c. circuit, a capacitor can conduct but not an inductor.
B. In a d.c. circuit, an inductor can conduct but not a capacitor.
C. In a d.c. circuit, both the inductor and capacitor cannot conduct.
D. An inductor has infinite resistance in a d.c. circuit.

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The mutual inductance of a pair of coils placed close to each other depends upon
If the number of turns in a coil is tripled, the value of the magnetic flux linked with the coil:
A wire shown in figure carries a current of 10 A. The magnitude of the magnetic field at the centre O is: (Given: radius of the bent coil is 3 cm.)
A 0.5 m long solenoid has 500 turns and has a flux density of \(2.52 \times 10^{-3}\) T at its center. The current in the solenoid is (Given, \(\mu_0 = 4\pi \times 10^{-7}\) H/m)
Identify the correct statements among the following.
A. The torque acting on a planar current loop in a magnetic field changes when its shape is changed without changing its area.
B. Two parallel wires carrying currents in opposite directions attract each other.
C. An ideal ammeter has zero resistance and an ideal voltmeter has infinite resistance.
D. A galvanometer can be converted into a voltmeter by connecting a high resistance in series.

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A bar magnet of dipole moment 3 Am2 rests with its centre on a frictionless point. A force F is applied at right angles to the axis of the magnet, 10 cm from the point. It is observed that an external magnetic field of 0.25 T is required to hold the magnet in equilibrium at an angle of \(30^{\circ}\) with the field. The value of F is: