Question

Correct answer with clear explanation please.

1.which of the following is a characteristic of electrical insulator?

a. electrical field inside it is always zero

b. charge placed on it or inside it will not move

c. it can't be affected in any way by an external electric field.

d. charge placed on it or inside it will distribute itself on its outer surface.

2. A light bulb operating at a DC voltage of 120V has a resistance 200 omega. how much power is dissipated in this bulb?

I used P = (V^2) / R, and got 72W. Is this correct way of solving it?

3. 5.0 F, 14 F, and 21 F capacitor are connected in series. How much capacitance would a single capacitor need to have to replace the three capacitor?

I used equation 1/C_eq = 1/5 + 1/14 + 1/21

so, 1/C_eq = 42/210 + 15/210 + 10/210 = 67/210

C_eq = 210/67 = 3.1F

Is this correct way of solving it?

4. Ideal gas in a container of Volume V at pressure P. rms speed of a gas molecule under this condition is v. If condition change to 2V and 2P, the rms speed of a molecule will be what?

Please show me the calculation.

5. Ideal gas has a molar specific heat at constant pressure of 7R/2. What is its molar specific heat at constant volume?

Please show me the calculation.

Answer 1

1)(b)charge placed on it or inside it will not move

Becaudse, insulator are the materials which apposes the flow of electron/charge because their atoms have very tightly bound electrons and hence they are not free to move within the material.

2)We know that,

P = I^2R

I = V/R = 120/200 = 0.6

P = I^2 R = 0.6^2 x 200 = 72 Watts

Hence, P = 72 Watts

(You are correct)

3)The equivalent of capacitors in series would be:

1/Ceq = 1/5 + 1/14 + 1/21 => C = 3.13 F

Hence, Ceq = 3.13 F

(you are correct)

4)V(rms) = sqrt (3 RT/M)

T1 = P1V1/nR = PV/nR

T2 = P2V2/nR = 4PV/nR

T2 = 4 T1

V = sqrt (3 R T1/M)

V^2 = 3 r T1/M

V' = sqrt (3 R (4T1)/M)

V'^2 = 12 R T1/ M

V'^2/V^2 = 4

V' = sqrt (4 v^2) = 2V

Hence, V' = 2 V