Advertisements
Advertisements
प्रश्न
A capacitor of unknown capacitance is connected across a battery of V volts. The charge stored in it is 300 μC. When potential across the capacitor is reduced by 100 V, the charge stored in it becomes 100 μC. Calculate The potential V and the unknown capacitance. What will be the charge stored in the capacitor if the voltage applied had increased by 100 V?
Advertisements
उत्तर
(i) Initial voltage, V1 = V volts, Charge stored,Q1 = 300 µC
Q1 = CV1 ..(1)
Changed potential, V2 = V-100 V
Q2 = 100 µC
Q2 = CV2 ..(2)
By dividing (2) from (1), we get `(Q_1)/(Q_2) = (CV_1)/(CV_2) => Q_1/Q_2 = V_1 /V_2`
`=> 300/100 = V/(V- 100) => V = 150 \text { volts }`
`∴ C = Q_1/V_1 = (300 xx 10^-6)/150 = 2 xx 10^-6 F = 2 μ F`
(ii) If the voltage applied had increased by 120 V, then V3 = 150+100 = 250 V
Hence, charge stored in the capacitor, Q3 = CV3 = 2×10-6×250 = 500 µC
(ii) If the voltage applied had increased by 120 V, then V3 = 150+100 = 250 V
Hence, charge stored in the capacitor, Q3 = CV3 = 2×10-6×250 = 500 µC
APPEARS IN
संबंधित प्रश्न
(i) Find equivalent capacitance between A and B in the combination given below. Each capacitor is of 2 µF capacitance.
(ii) If a dc source of 7 V is connected across AB, how much charge is drawn from the source and what is the energy stored in the network?
Two identical capacitors of 12 pF each are connected in series across a battery of 50 V. How much electrostatic energy is stored in the combination? If these were connected in parallel across the same battery, how much energy will be stored in the combination now?
Also find the charge drawn from the battery in each case.
The outer cylinders of two cylindrical capacitors of capacitance 2⋅2 µF each, are kept in contact and the inner cylinders are connected through a wire. A battery of emf 10 V is connected as shown in figure . Find the total charge supplied by the battery to the inner cylinders.
Each of the capacitors shown in figure has a capacitance of 2 µF. find the equivalent capacitance of the assembly between the points A and B. Suppose, a battery of emf 60 volts is connected between A and B. Find the potential difference appearing on the individual capacitors.
Find the equivalent capacitance of the infinite ladder shown in figure between the points A and B.
Obtain an expression for equivalent capacitance when three capacitors C1, C2 and C3 are connected in series.
Explain in detail the effect of a dielectric placed in a parallel plate capacitor.
During a thunder storm, the movement of water molecules within the clouds creates friction, partially causing the bottom part of the clouds to become negatively charged. This implies that the bottom of the cloud and the ground act as a parallel plate capacitor. If the electric field between the cloud and ground exceeds the dielectric breakdown of the air (3 × 106 Vm–1), lightning will occur.
- If the bottom part of the cloud is 1000 m above the ground, determine the electric potential difference that exists between the cloud and ground.
- In a typical lightning phenomenon, around 25 C of electrons are transferred from cloud to ground. How much electrostatic potential energy is transferred to the ground?
Two spherical conductors A and B of radii a and b(b > a) are placed concentrically in the air. B is given a charge +Q and A is earthed. The equivalent capacitance of the system is ______.
A parallel plate capacitor (A) of capacitance C is charged by a battery to voltage V. The battery is disconnected and an uncharged capacitor (B) of capacitance 2C is connected across A. Find the ratio of final charges on A and B.
