A $30\,\mu F$ capacitor is charged by a constant current of $30\, mA$. If the capacitor is initially uncharged, how long does it take for the potential difference to reach $400\, V$.....$s$
A $30\,\mu F$ capacitor is charged by a constant current of $30\, mA$. If the capacitor is initially uncharged, how long does it take for the potential difference to reach $400\, V$.....$s$
- A
$0.1$
- B
$0.2$
- C
$0.3$
- D
$0.4$
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Answer carefully:
$(a)$ Two large conducting spheres carrying charges $Q _{1}$ and $Q _{2}$ are brought close to each other. Is the magnitude of electrostatic force between them exactly given by $Q _{1} Q _{2} / 4 \pi \varepsilon_{0} r^{2},$ where $r$ is the distance between their centres?
$(b)$ If Coulomb's law involved $1 / r^{3}$ dependence (instead of $1 / r^{2}$ ), would Gauss's law be still true?
$(c)$ $A$ small test charge is released at rest at a point in an electrostatic field configuration. Will it travel along the field line passing through that point?
$(d)$ What is the work done by the field of a nucleus in a complete circular orbit of the electron? What if the orbit is elliptical?
$(e)$ We know that electric field is discontinuous across the surface of a charged conductor. Is electric potential also discontinuous there?
$(f)$ What meaning would you give to the capacitance of a single conductor?
$(g)$ Guess a possible reason why water has a much greater dielectric constant $(=80)$ than say, mica $(=6)$
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