Please select a subject first
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A cell of internal resistance r is connected across an external resistance nr. Then the ratio of the terminal voltage to the emf of the cell is ______.
Concept: undefined >> undefined
Two trains are moving towards each other with speeds of 20m/s and 15 m/s relative to the ground. The first train sounds a whistle of frequency 600 Hz. The frequency of the whistle heard by a passenger in the second train before the train meets, is ______. (the speed of sound in air is 340 m/s)
Concept: undefined >> undefined
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A ray of light is incident normally on a glass slab of thickness 5 cm and refractive index 1.6. The time taken to travel by a from source of slab is same as to travel through glass slab. The distance of source from the surface is ______.
Concept: undefined >> undefined
A string is vibrating in its fifth overtone between two rigid supports 2.4 m apart. The distance between successive node and antinode is ______.
Concept: undefined >> undefined
A mass is suspended from a vertical spring which is executing S.H.M. of frequency 5 Hz. The spring is unstretched at the highest point of oscillation. Maximum speed of the mass is ______. [acceleration due to gravity g = 10 m/s2]
Concept: undefined >> undefined
The frequencies for series limit of Balmer and Paschen series respectively are 'v1' and 'v3'. If frequency of first line of Balmer series is 'v2' then the relation between 'v1', 'v2' and 'v3' is ______.
Concept: undefined >> undefined
When the same monochromatic ray of light travels through glass slab and through water, the number of waves in glass slab of thickness 6cm is same as in water column of height 7cm. If refractive index of glass is 1.5, then refractive index of water is ______.
Concept: undefined >> undefined
A particle performing SHM starts equilibrium position and its time period is 16 seconds. After 2 seconds its velocity is π m/s. Amplitude of oscillation is ______. `(cos 45° = 1/sqrt2)`
Concept: undefined >> undefined
In potentiometer experiment, null point is obtained at a particular point for a cell on potentiometer wire x cm long. If the length of the potentiometer wire is increased without changing the cell, the balancing length will ______. (Driving source is not changed)
Concept: undefined >> undefined
In balanced meter bridge, the resistance of bridge wire is 0.1 Ω cm. Unknown resistance X is connected in left gap and 6 Ω in right gap, null point divides the wire in the ratio 2:3. Find the current drawn from the battery of 5 V having negligible resistance.
Concept: undefined >> undefined
A mass m1 connected to a horizontal spring performs SHM with amplitude A. While mass m1 is passing through mean position, another mass m2 is placed on it so that both the masses move together with amplitude A1. The ratio of `"A"_1/"A"` is ______. (m2 < m1)
Concept: undefined >> undefined
In the hydrogen atoms, the transition from the state n = 6 to n = 1 results in ultraviolet radiation. Infrared radiation will be obtained in the transition.
Concept: undefined >> undefined
If the absolute temperature of a gas is increased 5 times, then the rms velocity of the gas molecules will be ______.
Concept: undefined >> undefined
A vessel of depth 2d cm is half filled with a liquid of refractive index μ1 and the upper half with liquid of refractive index μ2, the apparent depth as seen normally is ______.
Concept: undefined >> undefined
A small bulb is placed at the bottom of a tank containing water to a depth of 80 cm. What is the area of the surface of water through which light from the bulb can emerge out? Refractive index of water is 1.33. (Consider the bulb to be a point source)
Concept: undefined >> undefined
A point source S is placed at the bottom of a transparent block of height 10 mm and refractive index 2.72. It is immersed in a lower refractive index liquid as shown in the figure. It is found that the light emerging from the block to the liquid forms a circular bright spot of diameter 11.54 mm on the top of the block. The refractive index of the liquid is ______.

Concept: undefined >> undefined
A transparent solid cylindrical rod has a refractive index of `2/sqrt3`. It is surrounded by air. A light ray is incident at the midpoint of one end of the rod as shown in the figure. The incident angle θ for which the light ray grazes along the wall of the rod is ______.

Concept: undefined >> undefined
Light of wavelength 6000 Å incident on a single slit. The first minimum of the diffraction pattern is obtained at 4 min from the centre. The screen is at a distance of 2m from the silt. The slit width will be ______.
Concept: undefined >> undefined
The frequency of the series limit of the Balmer series of the hydrogen atoms of Rydberg’s constant R and velocity of light c is ______.
Concept: undefined >> undefined
Light of wavelength 6000 Å falls on a single slit of width 0.1 mm. The second minimum will be formed for the angle of diffraction of ______.
Concept: undefined >> undefined
