Skip to main content
A

Anonymous

Jan 05, 2025

A parallel-plate air capacitor has a capacitance of 920 pF. The charge on each plate is 2.55 uC?

A parallel-plate air capacitor has a capacitance of 920 pF, and the charge on each plate is 2.55 μC. What is the potential difference between the plates? If the charge is kept constant, what will be the potential difference if the separation between the plates is doubled? Additionally, how much work is required to double the separation?

4 Answers

A
Anonymous

Feb 17, 2025

1st answer is correct with respect to the potential differences before and after doubling the separation. However, work is equal to the change in potential energy stored in the capacitor.

PE = V^2C/2.

The separation doubles PE because it quadruples V^2 while halving C.

PE1 = V1^2*C1/2 = 3.5339674E-03 J

C2 = C1/2

V2 = 2V1

PE2 = V2^2*C2/2 = 4V1^2*C1/4 = V1^2*C = 2PE1 = 7.0679348E-03 J

Work = PE2-PE1 = PE1 = 3.5339674E-03 J

V = Q/C = 2.55 * 10^-6/920 * 10^-12 = 0.00277 * 10^6 = 2.77 * 10^3 V

V = Q/C = Qd/AEo

if seperation is doubled, potential also doubles!

W = Q(V2 – V1) = QV = 2.55 * 10^-6 * 2.77 * 10^3 = 7.0635 * 10^-3 J

A
Anonymous

Feb 10, 2025

Q is constant:

C1 = eo A/d1

C2 = eo A/(2*d1) = (C1 / 2)

U1 = Q^2/C1/2

U2 = Q^2/C1

delta_work = U2 – U1 = Q^2/C1/2

delta_work = 0.00353396739 J

A
Anonymous

Feb 18, 2025

(a) By C = εo x A/d =>d = (εo x A)/C =>d = (8.85 x 10^-12 x 1.2 x 10^-4)/(5.7 x 10^-12) =>d = 1.86 x 10^-4 m =>d = 0.186 mm (b) By E = 1/2CV^2 =>E = 1/2 x 5.7 x 10^-12 x (220)^2 =>E = 1.38 x 10^-7 J (c) By C’ = C x k =>C’ = 5.7 x 10^-12 x 3.5 =>C’ = 19.95 (pF) By C = Q/V =>Q = V x C’ =>Q = 220 x 19.95 x 10^-12 =>Q = 4.39 x 10^-9 C

Want to answer this question?

Join our community to share your knowledge!

Related Questions

1
If this same quantity of energy were transferred to 2.5 kg of water at its boiling point, what fraction of the water would be vaporized?

"If this same quantity of energy were transferred to 2.5 kg of water at its boiling point, what fraction of the water wo...

3
A question for bike riders, How come the back wheel is always following the front one, Is that odd or what. ?

Have you ever noticed how the rear wheel of a bike seems to follow the front wheel closely? Why does this happen, and is...

3
Identify each of the following as measurements?

Please identify each of the following as measurements: Length Area Volume Mass Density Time Temperature...

1
Today’s CPUs run at speeds measured in kilohertz.?

Today's CPUs operate at speeds measured in gigahertz rather than kilohertz. Is this statement true or false?

2
a question regarding torque in a magnetism setting?

I have a question regarding torque in a magnetism context. I understand that the equation τ = IABsin(θ) will be relevant...

1
How do you do this work and energy problem? physics urgent help!?

A 4.5 kg box slides down a 4.4 m high frictionless hill, starting from rest. It then travels across a 2.4 m wide horizon...

3
How is friction involved in sledding and skiing?

How does friction play a role in sledding and skiing? Specifically, what are the effects of friction on speed, control,...

10
what is the speed of light (in kilometers an hour)?

What is the speed of light in kilometers per hour?

1
Find the current through each resistor HELPP!!?

I need help finding the current through each resistor in the following circuit: http://session.masteringphysics.com/prob...

4
how do you draw the energy level diagram for aluminum?

What are the steps to create an energy level diagram for aluminum? Could you provide detailed guidance on how to accurat...