Electric Circuits Answers

A capillary tube is immersed in water of surface tension 70 x 10-2 Nm-1 and rises 6.2 cm. By what depth will mercury be depressed if the same capillary is immersed in it? (Surface tension of mercury = 0.54 Nm-1; angle of contact between mercury and glass = 140 degrees, density of mercury = 13600 kgm-3)

A capillary tube of 0.4 mm diameter is placed vertically inside (i) water of surface tension 6.5 x 10-2 Nm-1 and zero angle of contact, (ii) a liquid of density 800 kgm-3, surface tension 5.0 x 10-2 Nm-1 and an angle of contact 30 degrees. Calculate the height to which the liquid rises in the capillary in each case.

What are the dimensions of surface tension?

If water has a surface tension of 7 x 10^2 Nm and an angle of contact with water of zero. At what height does it rise in a capillary of diameter 0.5 mm?
What are the dimensions of surface tension?

Two plane parallel conducting plates 1.50 cm apart are held horizontal, one above the other in air. The upper plate is maintained at a positive potential of 1500 volts while the other lower plate is earthed. (a) Calculate the number of electrons which must be attached to a small oil drop of mass 4.90 x 10-12g, if it remains stationary in the air between the plates. (Assume that the density of the air is negligible in comparison with that of oil.) (b) If the potential of the upper plate is suddenly changed to -1500 volts, what is the initial acceleration of the charge drop? Indicate, giving reasons, how the acceleration will change.

A charged oil-drop of radius 1.3 x 10-4cm is prevented from falling under gravity by the vertical field between two horizontal plates charged to a difference of potential of 8340 volts. The distance between the plates is 1.6 cm, and the density of oil is 920kgm-3. Calculate the magnitude of the charge on the drop.

Define (a) electric intensity (b) difference of a potential. How are these quantities related?

A small object of mass 15 g carries a charge 3400 C and is suspended by a thread between the vertical plates of a parallel-plate capacitor. The plate separation is 3.55 cm. If the thread makes an angle of 10 degrees with the vertical, what is the potential difference between the plates?

A fully charged parallel-plate capacitor remains connected to a battery while you slide a dielectric between the plates. Do the following quantities increase, decrease or remain the same? (i) C (ii) Q (iii) Change in V (iv) the energy stored in the capacitor

Two particles, with charges of 20.0 nC and 40.0 nC are placed at the points with coordinates (0, 4.00 cm) and (3.00 cm, 0). A particle with charge 10.0 nC is located at the origin. (a) Find the electric potential energy of the configuration of the three fixed charges.