Answer: B. 45. What is correct equation for node B (Fig.7), if we apply node voltage analysis?

 

45. What is correct equation for node B (Fig.7), if we apply node voltage analysis? (G=1/R)

A.– 2Gv_A- 0.5Gv_B+3.5Gv_C=0 B. 2Gv_A- 0.5Gv_B+3.5Gv_C=0

C. 0.5Gv_A+3Gv_B-0.5Gv_C =0 D. – 0.5Gv_A+3Gv_B-0.5Gv_C=0

E. 2.5Gv_A-0.5Gv_B -2Gv_C=i_S Fig. 7

 

Solution:

V_B(0.5G+2G+0.5G) –V_A(0.5G) –V_C(0.5G)=0

–0.5GV_A+3GV_B–0.5GV_C=0

Answer: D.

 

 

46. Formulate mesh-current equation for mesh A for the circuit in Fig.8.

 

A. (R₃+R₄)i_B-R₃i_C= v_S2 B. (R₁+R₂)i_A-R₂i_C= v_S2

C. (R₃+R₂)i_C-R₃i_C- R₂i_A= v_S1

D. (R₃+R₂)i_C-R₃i_C- R₂i_A= -v_S1 E. (R₁+R₂)i_A-R₂i_C= - v_S2

 

Solution:

i_A(R₁+R₂) – i_CR₂= –V_S2 Fig.8

Answer: E.

 

 

47. To apply superposition principle we must ______ in turn all sources, except one. When the current source is _________, we replace it by _________.

A. “turn on”, turned off, short circuit. B. “turn off”, turned on, open circuit.

C. “turn off”, turned on, short circuit. D. “turn off”, turned off, open circuit.

E. “turn off”, turned off, short circuit.

 

Solution:

To apply superposition principle we must “turn off” all sources in turn. When the current source is turned off, we replace it be open circuit.

Answer: D.

 

48. Ideal voltage source is described as v=____ and i=____, but ideal current source – i=_____, v=_____.

A. v_S, any value, i_S, any value B. any value, i_S, any value, v_S

C. v_S, i_S, any value, any value D. any value, any value, i_S, v_S

E. all answers are wrong

 

Solution:

Ideal voltage source is described as v= v_S and i= any value, but ideal current source – i= i_S, v= any value.

Answer: A.

 

49. Find the correct formula for p. p =

A. vi B. dw/dq C.dq/dt D. dq/dv E. di/dt

Solution: p=dw/dt=vi.

Answer: A.

 

50. The parameters of the Thevenin and Norton equivalent circuits at a given interface can be found as

A. v_T=v_SC i_N=i_OC R_N=R_T=v_OC/i_SC B. v_T=v_OC i_N=i_SC R_N=R_T=v_OC/i_OC

C. v_T=v_SC i_N=i_OC R_N=R_T=v_SC/i_SC

D. v_T=v_SC i_N=i_OC R_N=R_T=v_OC/i_OC E. v_T=v_OC i_N=i_SC R_N=R_T=v_OC/i_SC

 

Solution:

v_T=v_OC i_N=i_SC R_N=R_T=v_OC/i_SC