# XII_Physics_Current Electricity_8 Online Test

The plates of a capacitor are charged to a potential difference of 100V and are then connected across a resistor. The p.d across the capacitor decays exponentially with time After 1 s the potential difference between the plates of the capacitor is 80 volt. What is the fraction of the stored energy which has been dissipated?
1/25
1/5
9/25
16/25
Electric intensity is ____.
a scalar quantity
a vector quantity
neither scalar nor vector
sometimes scalar and sometimes vector
If two electrons are separated by a distance of 0.5A, then ratio of coulomb force and weight of electron is approximately ____.
1016
1018
1020
1022
Three charges –q, Q and –q are placed at equal distance on a straight line. If the total potential energy of the system of three charges is zero, then the ratio Q : q is ____.
1 :2
2 :1
1 : 1
1 : 4
Two positively charged particles each of mass 1.7 x 10-27 kg and carrying a charged of 1.6 x 10-19 are placed at a distance r apart. If each one experiences a repulsive force equal to its weight, then r is ____.
1.17 m
1.71 m
0.117 m
0.171 m
A pendulum bob of mass 80 milligrams and carrying a charge of 2 x 10-8 C is at rest in a uniform horizontal electric field of 20000 V/m. The angle which it makes with the vertical is ____.
tan-1 (0.81)
tan-1 (0.71)
tan-1 (0.51)
tan-1 (0.41)
How many electrons constitute a current of one microampere?
6.25 x 106
6.25 x 1012
6.25 x 109
6.25 x 1015
An air filled parallel-plate capacitor has a capacitance of 10-12 fared. Separation of the plates is doubled and wax inserted between them, which makes the capacitance 2 x 10-12 fared. This implies that the dielectric constant of the wax is
2.0
3.13
4.0
8.00
Which switch in the circuit when closed will produce short-circuiting? 
A
B
C
None of the above
The plates of a parallel plate’s air capacitor are 2 cm apart. A slab of dielectric constant 5 and thickness 1 cm is placed between the plates with its faces parallel to them and the distance between the plates is altered so as to keep the capacitance of the new capacitor unchanged. The new separation between the plates is ____.
2.2 cm
2.8 cm
3.0 cm
3.2 cm
Description:

This test consist of 10 questions.Students should ideally take 10 minutes to complete the test. This test is useful for those students who are preparing for IIT JEE, AIEEE or any other engineering entrance test. This test consist of questions from Current Electricity and which, in general, is focused in AIEEE and IIT JEE. In this chapter, Cells, emf and internal resistance are key topic and mostly application based questions are asked.

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