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Condition |
free/or 0.5$ |
| 821 | N sources of current with different emf's are connected as shown in Fig. 3.40. The emf's of the sources are proportional to their internal resistances, i.e. ξ = αR, where α is an assigned constant. The lead wire resistance is negligible. Find: (a) the current in the circuit; (b) the potential difference between points A and B dividing the circuit in n and N - n links. |
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| 822 | In the circuit shown in Fig. 3.41 the sources have emf's ξ1 = 1.0 V and ξ2 = 2.5 V and the resistances have the values R1 = 10 Ω and R2 = 20 Ω. The internal resistances of the sources are negligible. Find a potential difference φA - φB between the plates A and B of the capacitor C. |
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| 823 | In the circuit shown in Fig. 3.42 the emf of the source is equal to ξ = 5.0 V and the resistances are equal to R1 = 4.0 Ω and R2 = 6.0 Ω. The internal resistance of the source equals R = 0.10 Ω. Find the currents flowing through the resistances R1 and R2. |
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| 824 | Fig. 3.43 illustrates a potentiometric circuit by means of which we can vary a voltage V applied to a certain device possessing a resistance R. The potentiometer has a length l and a resistance R0, and voltage V0 is applied to its terminals. Find the voltage V fed to the device as a function of distance x. Analyse separately the case R >> R0. |
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| 825 | Find the emf and the internal resistance of a source which is equivalent to two batteries connected in parallel whose emf's are equal to ξ1 and ξ2 and internal resistances to R1 and R2. |
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| 826 | Find the magnitude and direction of the current flowing through the resistance R in the circuit shown in Fig. 3.44 if the emf's of the sources are equal to ξ1 = 1.5 V and ξ2 = 3.7 V and the resistances are equal to R1 = 10 Ω, R2 = 20 Ω, R = 5.0 Ω. The internal resistances of the sources are negligible. |
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| 827 | In the circuit shown in Fig. 3.45 the sources have emf's ξ1 = 1.5 V, ξ2 = 2.0 V, ξ3 = 2.5 V, and the resistances are equal to R1 = 10 Ω, R2 = 20 Ω, R3 = 30 Ω. The internal resistances of the sources are negligible. Find: (a) the current flowing through the resistance R1; (b) a potential difference φA - φB between the points A and B. |
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| 828 | Find the current flowing through the resistance R in the circuit shown in Fig. 3.46. The internal resistances of the batteries are negligible. |
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| 829 | Find a potential difference φA - φB between the plates of a capacitor C in the circuit shown in Fig. 3.47 if the sources have emf's ξ1 = 4.0 V and ξ2 = 1.0 V and the resistances are equal to R1 = 10 Ω, R2 = 20 Ω, R3 = 30 Ω. The internal resistances of the sources are negligible. |
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| 830 | Find the current flowing through the resistance R1 of the circuit shown in Fig. 3.48 if the resistances are equal to R1 = 10 Ω, R2 = 20 Ω, R3 = 30 Ω, and the potentials of points 1, 2, and 3 are equal to φ1 = 10 V, φ2 = 6 V, and φ3 = 5 V. |
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| 831 | A constant voltage V = 25 V is maintained between points A and B of the circuit (Fig. 3.49). Find the magnitude and direction of the current flowing through the segment CD if the resistances are equal to R1 = 1.0 S, R2 = 2.0 S, R3 = 3.0 S, and R4 = 4.0 S. |
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| 832 | Find the resistance between points A and B of the circuit shown in Fig. 3.50. |
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| 833 | Find how the voltage across the capacitor C varies with time t (Fig. 3.51) after the shorting of the switch Sw at the moment t = 0. |
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| 834 | What amount of heat will be generated in a coil of resistance R due to a charge q passing through it if the current in the coil (a) decreases down to zero uniformly during a time interval Δt; (b) decreases down to zero halving its value every Δt seconds? |
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| 835 | A dc source with internal resistance R0 is loaded with three identical resistances R interconnected as shown in Fig. 3.52. At what value of R will the thermal power generated in this circuit be the highest? |
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| 836 | Make sure that the current distribution over two resistances R1 and R2 c onnected in parallel corresponds to the minimum thermal power generated in this circuit. |
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| 837 | A storage battery with emf e = 2.6 V loaded with an external resistance produces a current I = 1.0 A. In this case the potential difference between the terminals of the storage battery equals V = 2.0 V. Find the thermal power generated in the battery and the power developed in it by electric forces. |
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| 838 | A voltage V is applied to a dc electric motor. The armature winding resistance is equal to R. At what value of current flowing through the winding will the useful power of the motor be the highest? What is it equal to? What is the motor efficiency in this case? |
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| 839 | How much (in per cent) has a filament diameter decreased due to evaporation if the maintenance of the previous temperature required an increase of the voltage by n = 1.0%? The amount of heat transferred from the filament into surrounding space is assumed to be proportional to the filament surface area. |
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| 840 | A conductor has a temperature-independent resistance R and a total heat capacity C. At the moment t = 0 it is connected to a de voltage V. Find the time dependence of a conductor's temperature T assuming the thermal power dissipated into surrounding space to vary as q = k (T — T0), where k is a constant, To is the environmental temperature (equal to the conductor's temperature at the initial moment). |
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