Answer: B. 143.What is equivalent capacitance for the circuit below respectively to terminals AB?

 

143. What is equivalent capacitance for the circuit below respectively to terminals AB?

A)4mF

B)16mF

C) 8mF

D)6mF

E). 10mF

Solution:

1/ C₁ =1/4+1/4;

C₁=4*4/(4+4)=2mF;

C_eq=2+3+5=10mF;

Answer: E

 

144. What is equivalent capacitance for the circuit below respectively to terminals AB?

A)1mF

B)2mF

C) 3mF

D)4mF

E)5mF

Solution:

1/ C₁ =1/2+1/2;

C₁=2*2/(2+2)=1mF

C_eq=3+1=4mF;

Answer: D

145. For the circuit on the right define V₀.

A)12V

B)6V

C)4V

D)3V

E)10V

Solution:

V₀=12*R/3R;

V₀=4V;

Answer: C

 

146. For the circuit in fig.19 the switch was in a neutral position. At t=0 it switches to position 1. What is the current of the transient?

A) 1- e^-500t A B) 0.5(1- e^-500t) A C). 2(1+e^-500t) A

D) 1+e^-500t A E). 0.5(1+e^-500t) A

Solution 1:

100/s =100I(s)+LsI(s)-Li_L(0); Fig.19

i_L(0)=0;

100/s=I(s)(100+0.2s);

I(s)=100/(100+0.2s)s=100/0.2s(500+s)=500/s(500+s);

A/s +B/(500+s) =500/s(500+s);

A500+As+Bs=500;

A500=500; s(A+B)=0;

A=1; A+B=0;

B=-1;

I(s)=1/s - 1/(500+s);

i(t)=1-e^-500t A

Solution 2:

i_L(t)=[ i_L(0)- i_L(¥)]*e^-t/Tc+ i_L(¥)

i_L(0)=0

i_L(¥)=Vs/R=100/100=1A

Tc=G_NL=0.2/100=0.002 s

i_L(t)=(0-1)* e^-t/0.002+ 1=1- e^-500t A

Answer: A

147. Main characteristics of sinusoidal waveform are

A)rms value, frequency

B). rms value, frequency, phase angle

C) rms value, frequency, amplitude

D) period, phase angle, rms value

E). amplitude, period, phase angle

Answer: E

 

148. What is equivalent inductance for the circuit?

A)1 mH

B). 2mH

C). 3mH

D) 4mH

E) 5mH

Solution:

1/ L₁=1/2+1/3+1/6; L₁=1mH;

L_eq=1+4=5mH;

Answer: E

 

149. This is notation of

A) operational amplifier

B) independent current source

C) independent voltage source

D) dependent current source

E) dependent voltage source