The given problem involves the ratio of electron and hole current, as well as the ratio of drift velocity of electrons and holes in a semiconductor. To determine the ratio of concentration of electrons and holes, we need to analyze the relationship between these parameters.

1. Current Ratio:
The ratio of electron current (Ie) to hole current (Ih) is given as 5:4. This means that for every 5 electrons flowing, there are 4 holes flowing in the opposite direction. This ratio indicates the relative number of charge carriers contributing to the current in a semiconductor.

2. Drift Velocity Ratio:
The ratio of drift velocity of electrons (Ve) to drift velocity of holes (Vh) is given as 7:4. Drift velocity is the average velocity of charge carriers in a semiconductor due to an applied electric field. This ratio indicates the relative speeds at which electrons and holes move in the semiconductor.

3. Relationship between Current and Drift Velocity:
The current in a semiconductor is directly proportional to the product of charge carrier concentration (n or p), charge (q), and drift velocity (V). Mathematically, it can be represented as: I = nqV.

4. Ratio of Concentration:
Let's assume the concentration of electrons as 'ne' and the concentration of holes as 'nh'. Since the current ratio is given as 5:4, we can write the relationship between electron and hole concentrations as: ne/nh = 5/4.

Similarly, since the drift velocity ratio is given as 7:4, we can write the relationship between electron and hole concentrations as: ne/nh = 7/4.

5. Solving the Equations:
From the above two equations, we can equate the ratio of electron and hole concentrations: 5/4 = 7/4.

Cross-multiplying, we get: 4 * 5 = 7 * nh.

Simplifying, we find: 20 = 7 * nh.

Dividing both sides by 7, we get: nh = 20/7.

Therefore, the ratio of concentration of electron and hole is 20/7.

Conclusion:
The equation involved in solving this problem is the relationship between current (I), drift velocity (V), and concentration (n) in a semiconductor (I = nqV). By equating the ratios of current and drift velocity for electrons and holes, we can determine the ratio of their concentrations. In this case, the ratio of electron and hole concentration is found to be 20/7.

Use I=neAv formula nd get ur answer