Electric current, drift velocity and mobility - Question Bank
1. If the temperature of a metallic conductor increases, the resistance increases because:
2. Which of the following quantities is a vector?
3. In a conductor, the mean free path of electrons is related to relaxation time and their average speed. A shorter mean free path implies:
4. The drift velocity is directly proportional to the applied electric field (E) and the mobility (μ). This relationship is expressed as:
5. If a conductor carries a current of 0.5 A, and the drift velocity of electrons is 2.5 x 10^-4 m/s, what is the effective cross-sectional area if the electron density is 10^28 m^-3?
6. Mobility of charge carriers is a property of the:
7. Which of the following statements about drift velocity is true?
8. If the number of free electrons per unit volume in a conductor is 'n', the current density (J) is given by:
9. The relaxation time (τ) is inversely proportional to:
10. What happens to the drift velocity if the cross-sectional area of the conductor decreases, while current and charge carrier density remain constant?
11. Mobility of charge carriers in semiconductors is generally:
12. The relationship between drift velocity (v_d) and current (I) for a conductor of cross-sectional area A is:
13. If the length of a conductor is doubled while keeping the voltage across it constant, the electric field strength:
14. Which material typically exhibits the highest mobility for its charge carriers?
15. In a conductor, the collisions of electrons with the lattice ions cause:
16. Mobility is defined as the magnitude of drift velocity per unit:
17. The drift velocity of charge carriers in a conductor is directly proportional to the product of relaxation time and:
18. A current of 1 A flows through a wire. If the cross-sectional area is 1 mm^2 and the number density of electrons is 10^29 m^-3, calculate the drift velocity.
19. Which of the following is NOT a factor determining mobility?
20. In most metallic conductors, the drift velocity of electrons is in the direction:
21. The direction of conventional current is defined as the direction of flow of:
22. If the number density of charge carriers (n) in a conductor decreases, and drift velocity remains the same, the current will:
23. Drift velocity is a consequence of the interaction between charge carriers and the:
24. Which statement is INCORRECT regarding electric current?
25. The mobility of electrons in copper is approximately 4.3 x 10^-3 m^2 V^-1 s^-1. If an electric field of 10^-2 V/m is applied, what is the drift velocity?
26. Consider a wire of length L and cross-sectional area A. If a voltage V is applied across its ends, the electric field E is approximately V/L. The drift velocity is proportional to:
27. A conductor has a current of 1.6 A. If the charge of an electron is 1.6 x 10^-19 C, how many electrons pass through a cross-section per second?
28. If the relaxation time of electrons in a conductor increases, the drift velocity will:
29. In the equation v_d = e E τ / m, 'm' represents:
30. Drift velocity (v_d) is related to relaxation time (τ) and electric field (E) by the equation:
31. The average time interval between two successive collisions of electrons in a conductor is called:
32. Ohm's law relates voltage, current, and resistance. It is a consequence of the microscopic description involving drift velocity when:
33. In a semiconductor, the charge carriers can be both electrons and holes. Their mobility values are generally:
34. Which of the following has higher mobility of charge carriers?
35. Mobility is a measure of how easily charge carriers can move under the influence of an electric field. Higher mobility means:
36. If the drift velocity of electrons in a conductor doubles, and other factors remain constant, the current will:
37. In the formula I = n A v_d e, 'e' represents:
38. The relationship between current (I), drift velocity (v_d), charge carrier density (n), and cross-sectional area (A) is given by:
39. As temperature increases, the drift velocity of electrons in a conductor generally:
40. Which of the following factors affects the drift velocity of electrons in a conductor?
41. The SI unit of mobility is:
42. Mobility of charge carriers is defined as:
43. The drift velocity of electrons in a conductor is generally:
44. When an electric field is applied across a conductor, the free electrons:
45. In a metallic conductor, the charge carriers responsible for electric current are:
46. What is drift velocity?
47. Which quantity is directly proportional to the electric current passing through a conductor?
48. If a charge of 10 Coulombs passes through a conductor in 2 seconds, what is the current?
49. Electric current is defined as the rate of flow of:
50. What is the SI unit of electric current?