A capacitor with a slab of glass between the plates is connected to a battery by Nichrome wires and allowed to charge completely. Then the slab of glass is removed. Describe and explain what happens. Include diagrams. If you give a direction for a current, state whether you are describing electron current or conventional current.

Short Answer

Expert verified

The electric field reduces, and capacitance increases, due to which charge storage decreases.

Step by step solution

01

Write the given data from the question.

The slab of the glass is placed between the plates of the capacitor.

After charging the completely, the glass slab removed from the capacitor.

02

Determine the formulas to calculate the capacitance of the capacitor.

The expression to calculate the capacitance of the capacitor when glass slab is placed between the plates is given as follows.

C=KAε0d

Here, Kis the dielectric constant of material, dis the distance between the plates,A area of the plates and ε0.

03

Determine the effect of removing the glass on the charge.

When the glass slab is placed between the plates, the electric field due to the glass slab is in the opposite direction of the electric field due to the plates. The net electric field is reduced, and capacitance increases, which increases stored charge.

The value for the air,Kair=1 , and for the glass,Kglass>1, by this we can see capacitance is increasing.

Therefore, the direction of the electric field and conventional current when the glass slab is placed between the plates are shown below.

If the glass slab is removed between the capacitor plates, the net electric field increases and capacitance decreases, due to which the charge storage decreases.

Therefore, the direction of the electric field and conventional current when the glass slab is removed between the plates are shown below.

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Most popular questions from this chapter

A circuit consists of a battery, whose emf is K, and five Nichrome wires, three thick and two thin as shown in Figure 19.78. The thicknesses of the wires have been exaggerated in order to give you room to draw inside the wires. The internal resistance of the battery is negligible compared to the resistance of the wires. The voltmeter is not attached until part (e) of the problem. (a) Draw and label appropriately the electric field at the locations marked × inside the wires, paying attention to appropriate relative magnitudes of the vectors that you draw. (b) Show the approximate distribution of charges for this circuit. Make the important aspects of the charge distribution very clear in your drawing, supplementing your diagram if necessary with very brief written descriptions on the diagram. Make sure that parts (a) and (b) of this problem are consistent with each other. (c) Assume that you know the mobile-electron density n and the electron mobility u at room temperature for Nichrome. The lengths (L1,L2,L3)and diameters(d1,d2) of the wires are given on the diagram. Calculate accurately the number of electrons that leave the negative end of the battery every second. Assume that no part of the circuit gets very hot. Express your result in terms of the given quantities(K,L1,L2,L3,d1,d2,nandu) . Explain your work and identify the principles you are using. (d) In the case thatd2d1 , what is the approximate number of electrons that leave the negative end of every second? (e) A voltmeter is attached to the circuit with its + lead connected to location B (halfway along the leftmost thick wire) and its - lead connected to location C (halfway along the leftmost thin wire). In the case thatrole="math" localid="1663035964741" d2d1 , what is the approximate voltage shown on the voltmeter, including sign? Express your result in terms of the given quantitiesrole="math" localid="1663036061574" (K,L1,L2,L3,d1,d2,nandu) .

Two resistor each with resistance of 4×106Ω are connected in series to a 60 V power supply whose internal resistance is negligible. You connect the voltmeter across one of these resistors and this voltmeter has an internal resistance of 1×106Ω. What is the reading on the voltmeter?

A circuit consists of two batteries (with negligible internal resistance), five ohmic resistors (Figure 19.88). The connecting wires that have negligible resistance. The letters A through are shown to make it possible to refer to specific parts of the circuit.

(a) Write all the equations necessary to solve for the unknown currents I1, I2, I3, I4 and I5, whose directions are indicated on the circuit diagram. Do not solve the equations but do explain very clearly what your equations are based on and to what they refer.

Assume that a computer program has solved your equations in terms of known battery voltages and known resistances so that the currents I1, I2,I3 ,I4and I5are are known. (b) In terms of known quantities calculate VD-VAand check that your sign makes sense. (c) In terms of known quantities, calculate the power produced in battery number 2.

Question: in circuit 1 (Figure 19.72), an uncharged capacitor is connected in series with two batteries and one light bulb. Circuit 2 (Figure 19.72) contains two light bulbs identical to the bulb in the circuit; in all other respects, it is identical to circuit 1. In circuit 1, the light bulb stays lit for 25 s. The following questions refer to these circuits. You should draw diagrams representing the fields and charges in each circuit at the times mentioned, in order to answer the questions.

(a)One microsecond after connecting both circuits, which of the following are true? Chose all that apply: (1) the net electric field at location B in circuit 1 is larger than the net electric field at location B in circuit 2. (2) At location A in 1, electrons flow to the left. (3) At location A in circuit 1, the electric fields due to charges on the surface of the wires and batteries points to the right. (4) in circuit 1 the potential difference across the capacitor plates is equal to the emf of the batteries. (5) The current in circuit 1 is larger than the current in circuit 2.

(b)Two seconds after connecting both circuits, which of the following are true? Choose all that apply: (1) there is more charge on the plates of capacitor 1 than there is on the plates of capacitor 2. (2) there is negative charge on the right plate of the capacitor in circuit 1. (3) At location B in circuit 2 the net electric field points to the right. (4) At location B in circuit 2 the fringe field of the capacitor points to the right. (5) At location A in circuit 1 the fringe field of the capacitor points to the left.

(c)Which of the graphs in Figure 19.73 represents the amount of charge on the positive plate of the capacitor in circuit 1 as a function of time?

(d)Which of the graphs in Figure 19.73 represents the current in circuit 1 as a function of time?

The circuit shown in Figure 19.61 consists of two flashlight batteries, a large air-gap capacitor, and Nichrome wire. The circuit is allowed to run long enough that the capacitor is fully charged with +Qand-Q on the plates.

Next you push the two plates closer together (but the plates don’t touch each other). Describe what happens, and explain why in terms of the fundamental concepts of charge and field. Include diagrams showing charge and field at several times.

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