The equation of a stationary wave is given as $\mathrm{y}=\mathrm{A}$ $\sin$ $0.5\mathrm{\pi t}$ $\cos (0.2\mathrm{\pi x}),$ $$ where t is in seconds and x in centimetres. Which of the following is correct?

A string is cut into three parts, having fundamental frequencies n₁, n₂, and n₃ respectively. The original fundamental frequency "n" is related by the expression:

1. $\frac{1}{n}=\frac{1}{n_1}+\frac{1}{n_2}+\frac{1}{n_3}$

2. $n=n_1\times n_2\times n_3$

3. $n=n_1+n_2+n_3$

4. $n=\frac{n_1+n_2+n_3}{3}$

A string of length l is fixed at one end and free at the other. If it resonates in different modes, then the ratio of frequencies is:

1. 1:2:3: ......

2. 1:3:5:7: ......

3. 1:2:4:8: ..........

4. 1:3:9: ........

The equation of a stationary wave is \(y = 0.8 ~cos\left(\frac{\pi x}{20}\right)sin200(\pi t)\)$$, where \(x\) is in cm and \(t\) is in sec. The separation between consecutive nodes will be:

1. \(20~\text{cm}\)

2. \(10~\text{cm}\)

3. \(40~\text{cm}\)

4. \(30~\text{cm}\)

An air column, closed at one end and open at the other, resonates with a tuning fork when the smallest length of the column is \(50\) cm. The next larger length of the column resonating with the same tuning fork will be:

A string of length 3 m and a linear mass density of 0.0025 kg/m is fixed at both ends. One of its resonance frequencies is 252 Hz. The next higher resonance frequency is 336 Hz. Then the fundamental frequency will be:
1. 84 Hz 

2. 63 Hz

3. 126 Hz 

4. 168 Hz

The fundamental frequency of a closed organ pipe of a length \(20\) cm is equal to the second overtone of an organ pipe open at both ends. The length of the organ pipe open at both ends will be:

In an experiment with a sonometer, a tuning fork of frequency 256 Hz resonates with a length of 25 cm and another tuning fork resonates with a length of 16 cm. If the tension of the string remains constant, then the frequency of the second tuning fork will be:

1. 163.84 Hz

2. 400 Hz

3. 320 Hz

4. 204.8 Hz

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 frequencies between these two. The lowest resonant frequency for these strings is:

A closed pipe and an open pipe have their first overtones identical in frequency. Their lengths are in the ratio: