Download App

Electrostatic Potential and Capacitance — Physics STD 12 Science — Question

Bihar BoardEnglish MediumSTD 12 SciencePhysicsElectrostatic Potential and Capacitance1 Mark
MCQ
A parallel plate capacitor is connected to a battery as shown in Fig. Consider two situations:
A: Key K is kept closed and plates of capacitors are moved apart using insulating handle.
B: Key K is opened and plates of capacitors are moved apart using insulating handle. Choose the correct option(s).

  • A
    In A : Q remains same but C changes.
  • B
    In B : V remains same but C changes.
  • C
    In A : V remains same and hence Q changes.
  • D
    In B : Q remains same and hence V changes.
✓

Answer

  1. In A : V remains same and hence Q changes.
  2. In B : Q remains same and hence V changes.

In case A, key K is kept closed and plates of capacitors are moved apart using insulating handle (i.e. distance between plates is increasing). As capacitance $\text{C}=\Big[\frac{(\text{K}\in_0\text{A})}{\text{d}}\Big]=\text{C}\propto\text{d}$ (separation between plates) so, capacitance will decrease & amount of charge stored will also decrease (as Q = CV). Here, there will be no change in potential difference.

In case B, key K is opened and plates of capacitors are moved apart using insulating handle, by conservation of charge, charge stored by the capacitor remains same. Plates of capacitance are moving apart so capacitance will decrease and with the decreases of capacitance, potential difference V increases $\Big(\text{as V}=\frac{\text{Q}}{\text{C}}\Big)$.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "M.C.Q [1M]" from Electrostatic Potential and Capacitance→Electrostatic Potential and Capacitance — all question types→Physics STD 12 Science question papers→Bihar Board STD 12 Science question papers→Bihar Board question paper generator→

Similar questions

Optical fibres are related with

(a) Communication

(b) Light

(c) Computer

(d) None of these
→
Potential energy is the characteristic of the:
→
The solar spectrums is :
→

A spherical surface of radius of curvature R separates air (refractive index 1.0) from glass (refractive index 1.5). The centre of curvature is in the glass. A point object P placed in air is found to have a real image Q in the glass. The line PQ cuts the surface at a point O, and PO = OQ. The distance PO is equal to

(a) 5 R

(b) 3 R

(c) 2 R

(d) 1.5 R

→

In an NPN transistor the collector current is 24 mA. If 80% of electrons reach collector its base current in mA is

(a) 36

(b) 26

(c) 16       

(d) 6
→
A plane electromagnetic wave with a single frequency moves in vacuum in the positive x direction. Its amplitude is uniform over the yz plane its wavelength:
→

In a step-up transformer, the turn ratio is 1 : 2. A Leclanche cell (e.m.f. 1.5V) is connected across the primary. The voltage developed in the secondary would be

(a) 3.0 V

(b) 0.75 V

(c) 1.5 V  

(d) Zero
→
In the circuit given in the figure, an a.c. source of 200 V is connected through a diode D to a capacitor. The potential difference across the capacitor will be

Image
→

Figure here shows P and Q as two equally intense coherent sources emitting radiations of wavelength 20 m. The separation PQ is 5.0 m and phase of P is ahead of the phase of Q by 90o. A, B and C are three distant points of observation equidistant from the mid-point of PQ. The intensity of radiations at A, B, C will bear the ratio

(a) 0 : 1 : 4

(b) 4 : 1 : 0

(c) 0 : 1 : 2

(d) 2 : 1 : 0
→

The coils of a step down transformer have 500 and 5000 turns. In the primary coil an ac of 4 ampere at 2200 volts is sent. The value of the current and potential difference in the secondary coil will be

(a) 20 A, 220 V

(b) 0.4 A, 22000 V

(c) 40 A, 220 V

(d) 40 A, 22000 V
→