Electrostatic Potential and Capacitance Quiz -02

1. A tiny spherical oil drop carrying a net charge q is balanced in still air with a vertical uniform electric field of strength 81π/7 x 105 V/m. When the field is switched off, the drop is observed to fall with terminal velocity 2×10-3 m/s. Given g=9.8 m/s², viscosity of the air= 1.8 x 10-5Ns/m² and the density of oil=900 kg/m³, the magnitude of q is

 
 
 
 

2. Two Capacitors C1 and C2 are charged to 120 V and 200 V respectively . It is found that by connecting them together  the potential on each one can be made zero. Then

 
 
 
 

3. A 4μF capacitor and a resistance of 2.5 MΩ are in series with 12 V battery. Find the time after which the potential difference across the capacitor is 3 times the potential difference across the resistor . [Given, ln(2)=0.693]

 
 
 
 

4. A dielectric slab of thickness d is inserted in a parallel plate capacitor whose negative plate is at x=0 and positive plate is at x=3d. The slab is equidistant from the plates. The capacitor is given some charge. As x goes from 0 to 3d.

 
 
 
 

5. Two large vertical and parallel metal plates having a separation of 1 cm are connected to a DC voltage source of potential difference X. A proton is released at rest midway between the two plates. It is found to move at 45º to the vertical just after release. Then X is nearly

 
 
 
 

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