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In Young's double-slit experiment, if the separation between coherent sources is halved and the distance of the screen from the coherent sources is doubled, then the fringe width becomes:
The current in an inductor of self-inductance $4 \text{ H}$ changes from $4 \text{ A}$ to $2 \text{ A}$ in $1 \text{ s}$. The emf induced in the coil is:
A hollow metal sphere of radius R is uniformly charged. The electric field due to the sphere at a distance r from the centre:
A string of length $l$ is fixed at both ends and is vibrating in second harmonic. The amplitude at antinode is $2\text{ mm}$. The amplitude of a particle at a distance $l/8$ from the fixed end is:
The angular width of the central maximum in the Fraunhofer diffraction for $\lambda = 6000 \text{ \AA}$ is $\theta_0$. When the same slit is illuminated by another monochromatic light, the angular width decreases by $30\%$. The wavelength of this light is:
Each of the two strings of lengths $51.6 \text{ cm}$ and $49.1 \text{ cm}$ is tensioned separately by $20 \text{ N}$ of force. The mass per unit length of both strings is the same and equals $1 \text{ g/m}$. When both the strings vibrate simultaneously, the number of beats is:
The magnetic flux linked to a circular coil of radius R is given by: $\phi = 2t^3 + 4t^2 + 2t + 5$ Wb. What is the magnitude of the induced EMF in the coil at $t = 5$ s?
A source of sound S emitting waves of frequency $100 \text{ Hz}$ and an observer O are located at some distance from each other. The source is moving with a speed of $19.4 \text{ ms}^{-1}$ at an angle of $60^\circ$ with the source-observer line as shown in the figure. The observer is at rest. The apparent frequency observed by the observer (velocity of sound in air $330 \text{ ms}^{-1}$), is:
In the above diagram, a strong bar magnet is moving towards solenoid-2 from solenoid-1. The direction of induced current in solenoid-1 and that in solenoid-2, respectively, are through the directions:
In the Young's double-slit experiment, the intensity of light at a point on the screen (where the path difference is $\lambda$) is $K$, where $\lambda$ is the wavelength of light used. The intensity at a point where the path difference is $\lambda/4$ will be
For a transparent medium, relative permeability and permittivity, $\mu_r$ and $\varepsilon_r$ are 1.0 and 1.44 respectively. The velocity of light in this medium would be:
A rod of length $L$ rotates with a small uniform angular velocity $\omega$ about its perpendicular bisector. A uniform magnetic field $B$ exists parallel to the axis of rotation. The potential difference between the centre of the rod and an end is:
An unpolarised light beam strikes a glass surface at Brewster's angle. Then:
A tuning fork with a frequency of $800 \text{ Hz}$ produces resonance in a resonance column tube with the upper end open and the lower end closed by the water surface. Successive resonances are observed at lengths of $9.75 \text{ cm}$, $31.25 \text{ cm}$, and $52.75 \text{ cm}$. The speed of the sound in the air is:
Twenty seven drops of same size are charged at $200 \text{ V}$ each. They combine to form a bigger drop. Calculate the potential of the bigger drop.
Light with an average flux of 20 W/cm² falls on a non-reflecting surface at normal incidence having a surface area of 20 cm². The energy received by the surface during a time span of 1 minute is:
The equation of state of some gases can be expressed as (P + a/V²)(V − b) = RT. Here P is the pressure, V is the volume, T is the absolute temperature and a, b, R are constants. The dimensions of ‘a’ are:
A linearly polarized monochromatic light of intensity 10 lumen is incident on a polarizer. The angle between the direction of polarization of the light and that of the polarizer such that the intensity of output light is 2.5 lumen is:
A student measured the diameter of a small steel ball using a screw gauge of least count $0.001\text{ cm}$. The main scale reading is $5\text{ mm}$ and zero of circular scale division coincides with $25$ divisions above the reference level. If the screw gauge has a zero error of $-0.004\text{ cm}$, the correct diameter of the ball is:
The ratio of the amplitude of the magnetic field to the amplitude of electric field for an electromagnetic wave propagating in vacuum is equal to: