Уровень

ЮЖНО-КАЗАХСТАНСКИЙ ГОСУДАРСТВЕННЫЙ УНИВЕРСИТЕТ ИМ. М.О.АУЕЗОВА

Естественно-педагогический факультет

Кафедра «Теория и методика преподавания физики»

Дисциплина: «Профессионально ориентированный иностранный язык»

Группа: ЕП-12-3к, ЕП-12-3р

Количество кредитов: 2

Количество вопросов: 75

уровень

1. Express Farad and Henry in terms of Ohms and seconds.

2. Express Ohm, Farad and Henry in terms of the basic SI quantities: ampere, second, kilogram and the metre.

3. The charge on a capacitor is doubled. By what factor does the capacitance change?

4. A steady current of 2 A flows through a 50 mH inductor for 10 s. What is the potential difference across the inductor?

5. Explain how the direction of self-induced emf is determined in an inductor

6. A 1 μF capacitor is charged up to a potential difference of 40 V.

a) What is the energy stored in the capacitor?

b) What is the charge of the capacitor?

7. Show that the formulas for the energy stored in a capacitor qU/2, q²/(2C) and CU²/2 are equivalent.

8. A charge of 10^–6 C is stored in a capacitor produces a 150 V potential difference. What is the energy of the capacitor?

9. What is the energy stored in the magnetic field of a 10 mH inductor, if it carries a 0,05 A current?

10. A 10 mH ideal inductor is connected in parallel with an ideal battery (with zero internal resistance). What is the work done by the battery in the interval during which the current increases from 1 A to 10 A?

11. The time dependence of the charge on the capacitor in an LC circuit is given by q(t)=0,1cos (10²πt) in μC.

a) What is the frequency of oscillations?

b) What is the maximum charge on the capacitor?

12. Charge oscillates in an ideal LC circuit by the equation: q(t) = 0,2 cos(500t) in mC. What is the amplitude of the charge oscillation?

13. The oscillation of charge in an LC circuit is given by q(t) = (10nC)∙cos(100 πt). What are the initial values of charge and current?

14. The instantaneous value of charge on the capacitor in an LC circuit is given by q(t) = (4μC)∙cos(10⁴ωt). The capacitance is 2 μF.

a) What is the maximum value of the voltage across the capacitor?

b) Express the potential difference across the capacitor as a function of time, U(t) =?

15. Charge oscillates in an ideal LC circuit by the equation: q(t) = 0,3∙cos(30t) in mC. What is the equation for the instantaneous value of current, i(t) =?

16. An LC circuit has a 10 μF capacitor and a 0,1 H inductor. What is the cyclic frequency of the EM oscillations?

17. An LC circuit is designed to have a natural cyclic frequency of 0,1 MHz. What is the inductance of the coil, if a 1 pF capacitor is used in the circuit?

18. An LC circuit has variable capacitance and inductance. The inductance of the circuit may range between 0,1μH and 10mH. The capacitance may vary between the limits 1pF–1μF. What is the range of cyclic frequencies that can be generated by this circuit?

19. An ideal LC circuit consists of a 25 μF capacitor and a 4 H inductor. At t = 0, the potential difference across the capacitor is 40 V and the current is zero. Write the time dependence of

a) voltage, U(t) =?

b) charge, q(t) =?

c) current, i(t) =?

20. A 2μF capacitor is charged up to a 220 V potential and connected to a 2 H inductor. Assume energy is not lost.

a) What is the potential across the capacitor t = 0,02π s after the capacitor starts to discharge?

b) What is the current in the circuit at a time t = 0,02π s after the capacitor starts to discharge?

21. Show that the cyclic frequency of free oscillations in an LC circuit is given by using the conservation of energy.

22. In a harmonic LC oscillation the maximum energy stored in the electric field is 4J and the maximum energy stored in the magnetic field is 4J. What is the total energy of the oscillations?

23. The maximum energy stored in the capacitor during electromagnetic oscillations in an LC circuit is 0,1 J.

a) What is the maximum energy in the inductor?

b) What is the total energy in the circuit?

24. The maximum values of charge and current are measured as q_m = 4 μC and I_m = 8 mA in an LC circuit. What is the cyclic frequency of oscillations? Assume there is no heat loss.

25. What is the ratio of energy stored in the inductor to the energy stored in the capacitor when 1/n of the total energy is stored in the capacitor of an LC circuit?