EASY
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The frequency of the fundamental note in a wire stretched under tension T is v. if the tension is increased to 25T, then the frequency of the fundamental note will be

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Important Questions on Wave Motion on a String

EASY
A string is stretched between fixed points separated by 75.0 cm. It is observed to have resonant frequencies of 420 Hz and 315 Hz. There are no other resonant frequencier between these two. The lowest resonant frequency for this string is:
MEDIUM
A wire of length 2L, is made by joining two wires A and B of same length but different radii r and 2r and made of the same material. It is vibrating at a frequency such that the joint of the two wires forms a node. If the number of antinodes in wire A is p and that in B is q then ratio p:q is:
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MEDIUM
If n1, n2 and n3 are the fundamental frequencies of three segments into which a string is divided, then the original fundamental frequency n of the string is given by:
EASY
A stretched wire of length 260 cm is set into vibrations. It is divided into three segments whose frequencies are in the ratio 2:3:4 . Their lengths must be
MEDIUM
Two wires W1 and W2 have the same radius r and respective, densities ρ1 and ρ2, such that ρ2=4ρ1 . They are joined together at the point O, as shown in the figure. The combination is used as a sonometer wire and kept under tension T. The point O is midway between the two bridges. When a stationary wave is set up in the composite wire, the joint is found to be a node. The ratio of the number of antinodes formed in W1 to W2 is 

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EASY
A stretched string fixed at both ends has m nodes, then the length of the string will be
MEDIUM
A string is clamped at both the ends and it is vibrating in its 4th harmonic. The equation of the stationary wave is y=0.3sin0.157x cos(200πt). The length of the string is
(All quantities are in SI units.)
HARD
Answer the following by appropriately matching the lists based on the information given in the paragraph.
A musical instrument is made using four different metal strings, 1, 2, 3 and 4 with mass per unit length μ,2μ,3μ and 4μ respectively. The instrument is played by vibrating the strings by varying the free length in between the range L0 and 2L0. It is found that in string- 1μ at free length L0 and tension T0 the fundamental mode frequency is f0.
List-I gives the above four strings while list-II lists the magnitude of some quantity.
 
  List I   List II
(I) String -1μ (P) 1
(II) String -22μ (Q) 12
(III) String -33μ (R) 12
(IV) String -44μ (S) 13
    (T) 316
    (U) 116

The length of the strings 1, 2, 3 and 4 are kept fixed at L0,3L02,5L04 and 7L04, respectively. Strings 1, 2, 3 and 4 are vibrated at their 1st, 3rd, 5th and 14th harmonics, respectively such that all the strings have same frequency. The correct match for the tension in the four strings in the units of T0 will be.
EASY
A standing wave is formed by the superposition of two waves travelling in opposite directions. The transverse displacement is given by, yx, t=0.5sin5π4xcos200πt. What is the speed of the travelling wave moving in the positive x direction? (x and t are in meter and second, respectively)
HARD
The total length of a sonometer wire fixed between two bridges is 110 cm. Now, two more bridges are placed to divide the length of the wire in the ratio 6:3:2. If the tension in the wire is 400 N and the mass per unit length of the wire is 0.01 kg m-1, then the minimum common frequency with which all the three parts can vibrate, is
HARD
Find the wrong statement form the following about the equation of stationary wave given by Y=0.04cosπxsin50πt m where t is in second. Then for the stationary wave.
EASY
In sonometer experiment, the string of length L under tension vibrates in second overtone between two bridges. The amplitude of vibration is maximum at
MEDIUM
A wire of length L and mass per unit length 6.0×10-3 kg m-1 is put under tension of 540 N. Two consecutive frequencies that it resonates at are: 420 Hz and 490 Hz. Then L in meters is :
MEDIUM
A string 2.0 m long and fixed at its ends is driven by a 240 Hz vibrator. The string vibrates in its third harmonic mode. The speed of the wave and its fundamental frequency is
MEDIUM
Answer the following by appropriately matching the lists based on the information given in the paragraph.
A musical instrument is made using four different metal strings, 1, 2, 3 and 4 with mass per unit length μ,2μ,3μ and 4μ respectively. The instrument is played by vibrating the strings by varying the free length in between the range L0 and 2L0. It is found that in string- 1μ at free length L0 and tension T0 the fundamental mode frequency is f0.
List-I gives the above four strings while list-II lists the magnitude of some quantity.
 
  List I   List II
(I) String -1μ (P) 1
(II) String -22μ (Q) 12
(III) String -33μ (R) 12
(IV) String -44μ (S) 13
    (T) 316
    (U) 116

If the tension in each string is T0, the correct match for the highest fundamental frequency in f0 units will be,
MEDIUM
Two strings of the same material and same length are given equal tension. If they are vibrating with fundamental frequencies 1600Hz and 900Hz, then the ratio of their respective diameters is
EASY
The equation of a stationary wave is y=2 sinπx15cos48πt. The distance between a node and its next antinode is
MEDIUM
A granite rod of 60 cm length is clamped at its middle point and is set into longitudinal vibrations. The density of granite is 2.7×103 kg m-3 and its Young's modulus is 9.27×1010 Pa. What will be the fundamental frequency of the longitudinal vibrations?
HARD
Two uniform wires of the same material are vibrating under the same tension. If the first overtone of the first wire is equal to the second overtone of the second wire and radius of the first wire is twice the radius of the second wire then the ratio of the lengths of the first wire to second wire is
MEDIUM
A sonometer wire of length 1.5m is made of steel. The tension in it produces an elastic strain of 1% . What is the fundamental frequency of steel if density and elasticity of steel are 7.7×103 kg m-3 and 2.2×1011 N m-2 respectively?