37) A 200-W light bulb is connected across 110 V. What current will flow through

Question

37) A 200-W light bulb is connected across 110 V. What current will flow through this bulb?
A) 0.90 A

B) 0.60 A

C) 0 A

D) 1.8 A

38) The length of a certain wire is doubled and at the same time its radius is increased by a factor of 4.
What is the change in the resistance of this wire?
A) It is reduced by a factor of 8.
B) It increases by a factor of 4.
C) It increases by a factor of 8.
D) It is reduced by a factor of 4.

39) Two capacitors of 4 F and 8 F are connected in parallel. What is the equivalent capacitance of this
system of capacitors?
A) 0.4 F

B) 2.7 F

C) 4 F

D) 12 F

40) A 4.0 F and a 6.0 F capacitor are connected in series across an 8.0-V DC source. What is the charge
on the 6.0 F capacitor?
A) 4.0 C

B) 25 C

C) 19 C

D) 2.0 C

41) A 5.0 F capacitor is connected in series with a 3.0 k resistor across a 20-V DC source and an open
switch. If the switch is closed at t = 0 s, what is the charge on the capacitor at t = 9 ms?
A) 37% of its minimum

B) 96% of its maximum

C) 45% of its maximum

D) 0 C

Explanation / Answer

1) P = VI

200 = 110*I

I = 200/110 = 1.8 A

2) Rold = (Rho)l/A

Area is proportional to r^2, hence area will be 16 times

Rnew = (Rho)*2/(16A) = 1/8*(Rho)*l/A

A) It is reduced by a factor of 8.

3) Equivalent capacitance in parallel

C = C1 + C2 = 4 + 8 = 12F

4)

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